Aegir/Strategy
NOTE: This page currently under construction.
(This page is for Aegir strategy guide. For the standard Aegir page, click here.)
Overview
Adapted with permission from the Housamo Gameplay-Based Tier List. Remove this disclaimer when Overview is sufficiently modified.
With the new Buff Snatch coming from him as well as somewhat favorable Push properties, 
Aegir offers unusual tools that can be exploited under the right circumstances. Buff Snatch is similar to Purge, except the erased buff is then transferred to him, this is especially useful to steal Guts, Evasion or other rare, non-scaling buffs he can make use of. It may sound quite great on paper, but it’s ultimately a glorified Purge due to the stolen buffs scaling off of enemy skill level, which is often not high enough. Past that, his LB1+LB2 offers a permanent push and lock thanks to Fear, allowing him to progressively push enemies up without repercussions. One very noteworthy aspect of his is also his Charge, being able to heal a lot of his HP back if it hits 2-3 enemies, which is heavily recommended. You can try and exploit his Charge for durability and damage (as 5☆ thanks to a nice offensive self-buff).
Christmas Aegir
Aegir (Christmas) occupies three particular gameplay niches: buff copier, buff stealer, and 
CharmCannot attack for 3 turns (Debuff) applicator. This first role is unique to Christmas Aegir and is arguably his most notable role: he can copy all ally buffs by moving, which can potentially allow him to do millions of damage. His second role is notable for the range of his buff steal, powercreeping his original variant's ability to buff steal and still being a relatively unique niche. Finally, Christmas Aegir has the unprecedented ability to charm enemies on turn start and can charm enemies while attacking, both at rather good procs. As a top performer in each of the above gameplay roles, Christmas Aegir is an excellent unit to have either as a specialist for high damage or as a generalist for regular use.
Highlights
Adapted with permission from the Housamo Gameplay-Based Tier List. Remove this disclaimer when Highlights is sufficiently modified.
Class: Disruptive Support
Gameplay role:
Pros
+ Default CP Up allows him to reach his fantastic Charge earlier.
+ LB1 Fear along with LB2 Push will allow him to shove back and hold enemy lines as much as he wants.
+ Buff Snatch is a Purge that, besides erasing enemy buffs progressively, he’ll reapply them to himself.
+ His Charge can heal him for about 40%~50% of his HP if he makes a full hit with it, helping a lot with his survivability.
Cons
- Only 5☆ has an offensive buff to himself, meaning 3☆ misses out on much-needed damage output.
- LB3 has a so-so proc rate, its effect relies on enemies having buffs to begin with and you can’t fully control what he could steal from them.
Christmas Aegir
Class: Bruiser, Disruptive Support
Gameplay role: Damage Dealer, Buff Copier, Buff Stealer, Charm Applicator
Pros
+ Can copy all buffs from adjacent allies to himself by moving, allowing for potentially deadly combinations
+ Can steal enemy buffs with large area of effect
+ Two methods of applying CharmCannot attack for 3 turns (Debuff), on turn start and attacking
+ Good baseline damage output due to 
BrawnATK Up by 1.15x ~ 2.3x for 4 turns (Buff), high ATK stat, and extra damage against 
Drain-10% skill activation rate, -10CP/turn for 2 turns (Debuff)
+ Immune to defensive debuffs, good chance of getting 
TenacityDEF Up by 0.9x ~ 0.45x for 1 turn (Buff) from attacking
Cons
- Lack of sustainability due to no access to healing, low HP
- Can't be buffed by 
RageATK Up and DEF Down by 1.25x ~ 2.5x for 2 turns (Buff) or 
BerserkATK Up and DEF Down by 1.3x ~ 2.6x for 4 turns (Buff) and their upgrades
- Selfish, not supporting allies outside of Charm, limiting team composition
- No innate ability to accumulate CP outside of CS
Gameplay Role
Christmas Aegir
Buff Copier
Aegir (Christmas) has the unique niche of being able to copy all of his allies' buffs to himself. There are a few things to note about this ability. First, the skill timing of this ability is when moving, restricting Christmas Aegir's buff copying in a certain way. Namely, he'll mostly benefit from buffs that activate on phase/turn start since they occur before Christmas Aegir can move. Similar logic appears to buffs that activate when appearing. As a consequence, he won't be able to copy a unit's buff that activates when moving, when/after attacking, or before/after receiving damage unless it rolls over into the next turn or if the skill applies it to him as well. For this reason, an unkillable Christmas Aegir by means of 
EvasionDEF Up by 0.01x ~ 0.005x for 1 turn (Buff) is unlikely to occur unless LW decides to release a unit with turn start Evasion. On the other hand, Christmas Aegir could theoretically do something akin to that effect with 
Guts+1HP when HP is at 0 at the end of the turn for 5 turns. Removed once activated. (Buff) by piggybacking off another unit's buff. The main point of note here is that Christmas Aegir mostly performs well with buffs of longer duration and he can only copy one turn buffs that are applied on phase/turn start.
The second point is that he'll benefit the most when his teammates have a variety of different buffs rather than repeated ones. Since Christmas Aegir for the most part is a selfish unit, this ideally means that the other three units of the team should be solid enough to work together fairly well while Christmas Aegir lends his support as a column deleter. It's slightly paradoxical, but it reflects the fact that Christmas Aegir provides little support for the team outside of killing and charming enemies. On the other hand, for one shot strategies, Christmas Aegir is the crux of the team so he'll work well even if his teammates don't necessarily synergize together by themselves.
The third point is that Christmas Aegir has pretty good damage that is consistent. An unseeded Christmas Aegir with BrawnATK Up by 1.15x ~ 2.3x for 4 turns (Buff) deals 5903 damage per square with 
Shot range and if extra damage against Drain-10% skill activation rate, -10CP/turn for 2 turns (Debuff) is possible, this number becomes 8863. So Christmas Aegir only really needs one or two offensive buffs to clear most enemies, and that's easily possible by buff copying or even by traditional means by having an offensive buffer as an ally. So although Christmas Aegir is a buff copier who can deal millions of damage potentially, it's important to remember that he can function outside such contexts as a reliable attacker who does not always have to move.
Finally, two Christmas Aegirs can trade buffs back and forth from each other in a similar manner as buff spreaders. From the previous points, this can be a viable strategy since Christmas Aegir is already a good attacker and can be used to implement the unkillable Christmas Aegir by means of Guts.
Buff Stealer
Christmas Aegir steals buffs in an interesting way that is worth explaining here. In the main effect of his LB2, it notes that he steals a buff from enemies at target and horizontally adjacent. As shown in the picture for Netter, this means that Christmas Aegir will take one buff from the enemy he hits, and also one buff each for any enemy to the left and right of the one he hit. This means that Christmas Aegir can steal up to nine buffs if he were to hit the middle column of a 3x3 square of enemies and successfully proc each time. Of course, he won't be able to steal buffs in a particular row if he doesn't hit an enemy inside the row. Furthermore, the buff steal is coupled in such a way that he either takes buffs from the entire row of enemies or he doesn't at all. For example, if there are three buffed enemies in a row and he were to hit the middle enemy, the skill will only proc once to decide if he steals three buffs or nothing at all.
Charm bot
Having two methods of applying CharmCannot attack for 3 turns (Debuff) to enemies, Christmas Aegir also does so at competitively high rates, making him the best applier of Charm in the game. His Charm on turn start is at a 40% rate unseeded, and if the effect procs, it allows the team to prioritize other enemies. Moreover, since it's on turn start, stalling and turnscumming can be performed to debilitate enemies by rerolling the die. On top of the first method, Christmas Aegir can apply Charm by attacking at a 30% proc. Since Christmas Aegir can easily copy buffs, 
Glint+10% skill activation rate for 2 turns (Buff), 
ConcentrationATK Up by 1.1x ~ 2.2x, skill activation rate +10% for 2 turns (Buff), and 
ComboATK Down by 0.6x (excepting charge attacks), attack twice each turn for 2 turns (Buff) are all possible methods to improve his activation rate.
Stats and Seed Usage
| Unit | (Effective) HP | Base ATK | ATK per square | CS ATK per square (SALV1) | ||||
|---|---|---|---|---|---|---|---|---|
| Unseeded | Seeded | Unseeded | Seeded | Unseeded | Seeded | Unseeded | Seeded | |
   |
5586 | 7467 | 4350 | 6032 | 2392 | 3318 | 3915 | 5429 |
  |
7536 | 9421 | 5243 | 6856 | 2884 | 3771 | 9437 | 12342 |
  |
6970 | 8832 | 5710 | 7337 | 2569 | 3302 | 10278 | 13207 |
Christmas Aegir
Skill seeds are appreciated here for guaranteeing Aegir (Christmas)'s buff copying ability, upping his CharmCannot attack for 3 turns (Debuff) and Drain-10% skill activation rate, -10CP/turn for 2 turns (Debuff) procs, and improving his buff stealing proc. There's quite a lot to benefit from here for consistency, but it's nothing really major. Regarding HP/ATK/Level seeds, HP seeds should be prioritized here since Christmas Aegir's base HP is relatively low. Moreover, using Christmas Aegir usually means that he'll have a load of offensive buffs already, so more ATK is generally overkill outside of pursuing bigger numbers.
Team Synergy
Christmas Aegir
Due to Aegir (Christmas)'s buff copying ability, he'll naturally pair well with units with various sources of buffs. There are many possible options here so here are some particular examples from each category:
Phase start Crit/Crit+
Wakan Tanka (Fashionista), 
Musashi, 
Kengo, and 
Tetsuya (Christmas) all have some form of 
Crit+ATK Up by 2.5x ~ 5x for 1 turn (Buff) or 
CritATK Up by 2x ~ 4x for 1 turn (Buff) on phase start with access to additional offensive buffs so these are all good candidates for teammates. There are likely other examples but this is a good starting point. Kengo in particular is a great teammate since his Crit is actually on turn start which means that Aegir can continually tap into burst damage.
Fashionista units
Except for 
Tsathoggua (Fashionista) due to his 
Immobility+12CP/turn, cannot move at will for 3 turns (Buff), the Fashionista units all around are particularly good due to their appliance of Ardor to allies and access to innate buffs on their own. "One of the best 
units in the game right now", 
Suzuka (Fashionista) is actually a nice teammate here due to her innate access to both Glint+10% skill activation rate for 2 turns (Buff) and ConcentrationATK Up by 1.1x ~ 2.2x, skill activation rate +10% for 2 turns (Buff), upping an unseeded Aegir's CharmCannot attack for 3 turns (Debuff) procs to 50%-60%.
Self-sufficient attackers
Krampus (Jiangshi) and 
Jinn are examples of self-sufficient attackers with offensive buffs that stack with Christmas Aegir's BrawnATK Up by 1.15x ~ 2.3x for 4 turns (Buff). Jiangshi Krampus in particular is interesting since he has turn start 
LimitATK Up by 1x~2x → 2x~4x as HP→0 for 1 turn (Buff), which can be very powerful if played correctly.
Phase start Evasion
Aside from Fashionista Wakan Tanka and Musashi mentioned already, units such as 
Sitri (Christmas) and 
Ose could be used so that Christmas Aegir can piggyback off their EvasionDEF Up by 0.01x ~ 0.005x for 1 turn (Buff) and have a free shot at charming enemies.
Offensive buffers
Finally, there are straightforward offensive buffers who preferably do not need to move. Some examples here are 
Claude (Christmas) and 
Tomte. Tomte in particular is great due to his access to 
AdamantineDEF Up by 0.9x ~ 0.45x for 4 turns (Buff) and ComboATK Down by 0.6x (excepting charge attacks), attack twice each turn for 2 turns (Buff) which Christmas Aegir can copy on top of all the buffs Tomte delivers.
CP batteries
Christmas Aegir's CP gain can be annoyingly slow, so having allies which can boost his CP is nice. 
Astaroth and 
Ziz are potentially interesting candidates for their other buffs.
AR Equipment
Christmas Aegir
Aegir (Christmas) doesn't have many good options for AR equipment yet as of time of writing, but he does have access to 
Shooting Stars which allows him to pierce EvasionDEF Up by 0.01x ~ 0.005x for 1 turn (Buff). This is very useful since Evasion is sometimes used to thwart first turn advantage in maps and because there are quite a few enemies who apply Evasion behind them.
Checks and Counters
Christmas Aegir
Movement inhibiting statuses
Since much of Aegir (Christmas)'s appeal depends on his movement, Statuss such as Immobility+12CP/turn, cannot move at will for 3 turns (Buff) and 
FearCannot move at will, -10CP/turn for 5 turns (Debuff) are particularly dangerous. This is an important note to beware of in both team composition with Christmas Aegir and having him face off against enemies since Christmas Aegir has both the ability to copy buffs from allies and steal buffs from enemies. Namely, do not use 
Chernobog (Beachside) with him carelessly.
Debuff reflection
Due to Christmas Aegir's multiple sources of CharmCannot attack for 3 turns (Debuff), he can be quickly shut down by an enemy with 
Reflect DebuffReflect debuff once for 4 turns. Vanishes after use. (Buff). If he doesn't proc Charm, he'll be hampered by Drain-10% skill activation rate, -10CP/turn for 2 turns (Debuff) at the very least.
Skill sealing
Christmas Aegir is not immune to skill sealing effects so 
BindCannot activate skills, ATK Down by 0.9x ~ 0.45x for 4 turns. CS effects still apply. (Debuff) and 
Skill LockCannot activate skills for 5 turns. (Debuff) are detrimental to him.
Teambuilding Options
This section consists of user-submitted builds that may not necessarily be viable for high level quests.
One Shot
| Team Details (submitted by milk) | |||||
|---|---|---|---|---|---|
 Takemaru 【Offensive Buffer】 |
Aegir 【Bruiser】 |
Kengo 【Offensive Buffer】 |
Wakan Tanka 【Support unit】 | ||
| Cost: ≥56 | |||||
This team is designed to grant Aegir (Christmas) a host of offensive buffs for potential challenge quests which may require such damage output. Namely, Christmas Aegir can be moved at turn start in order to have LimitATK Up by 1x~2x → 2x~4x as HP→0 for 1 turn (Buff), 
ATK UpATK Up by 1.1x ~ 2.2x for 4 turns (Buff), ConcentrationATK Up by 1.1x ~ 2.2x, skill activation rate +10% for 2 turns (Buff), BrawnATK Up by 1.15x ~ 2.3x for 4 turns (Buff), CritATK Up by 2x ~ 4x for 1 turn (Buff), 
InfinitudeATK Up by 1.3x ~ 2.6x, -400~-800HP for 1 turn (Buff), Crit+ATK Up by 2.5x ~ 5x for 1 turn (Buff), 
ArdorATK Up by 1.2x ~ 2.4x, +5CP/turn for 2 turns (Buff), and Guts+1HP when HP is at 0 at the end of the turn for 5 turns. Removed once activated. (Buff). This effectively translates to 7.14 million damage per square on phase one, turn one for an unseeded Christmas Aegir. Furthermore, if the enemy is not resistant to Drain-10% skill activation rate, -10CP/turn for 2 turns (Debuff) (which is unfortunately not the case for most challenge quests), Christmas Aegir has extra damage against this debuff which he applies himself, making the total number to be 10.7 million. These numbers can be increased through the use of seeds and ARs. Of course, this team assumes that Christmas Aegir can group his teammates, so this sort of strategy won't work for wide maps, at least in the beginning phase.