KakaniaBuild and Guide

Kakania is a 6-star Arcanist of the Plant Afflatus. One of the first properly defined "Tanks" in the game, Kakania is argued to be one of the top ranking Support/Sustain units. Her kit is geared towards soaking damage from allies and using it to deal tons of damage back and supercharging your Damage Dealer.

When allies take damage, Kakania redirects 50% of it to herself, storing a part of it as [Empathy] (up to a cap) which is the core of her kit. Whenever she stores a certain amount of [Empathy], she heals all allies based on her own HP, and whenever Kakania herself is healed, she deals Genesis DMG to all enemies based on her [Empathy].

But this stacking buff is used for a lot more. It increases the Genesis DMG dealt by "Subconcious", which is her 1-target attack incantation. In addition, the Genesis DMG dealt by "Id, Ego and Superego" (her Ultimate) is massively increased based on [Empathy] stacks; this incantation also records the damage enemies take after casting it, dealing a second instance of Genesis DMG at the end of the round based on the recorded damage.

More importantly, [Empathy] benefits "Association", which consumes Kakania's HP (if cast on an ally) but provides a large ATK buff called [Solace] to an ally that increases its potency based on her [Empathy]. If it is cast on herself, it restores a large chunk of HP instead.

Gameplay

Fun fact, Kakania's codename roughly translates to "Shitland". That's a ballsy name for a rights activist.

Ignoring that: straight up redirecting 50% of allied damage taken is probably the most effective form of tanking we have had so far; it doesn't rely on continuous casting like Shields and functions in all content unlike [Taunt]. With Kakania, gone are the days that allies randomly get exploded by bursts of high incoming damage.

Now, defensive supports usually aren't favored in gachas (unless obscenely overpowered) due to the rule of "the best mitigation is killing something before it kills you", so why does Kakania work? Two things: Genesis DMG and [Solace].

Her Genesis DMG output is pretty wild when paired with a passive healer like Tooth Fairy or Vila, and her Ultimate allows her to exploit extremely high bursts of damage coming from units such as Windsong or Spathodea to absolutely erase any health bar standing between you and the victory screen.

Then there's [Solace]. ATK buffs are few and far in between due to how high-value they are. Not only does Kakania have an extremely consistent one, it provides a flat 300 ATK + a percentage of ATK based on [Empathy], meaning that as the fight goes on it becomes stronger and stronger.

This all does mean that she is typically only used in long-form content, and her presence isn't as required in quick burst fights (i.e. UTTU/Story), but as more and more new content is introduced that can facilitate her presence (especially stuff like high diff Roguelike), Kakania continues to see increases in viability (even at her already high status).