Gecko fight denoscription

Starts immediately with the shield phase, the shield has 9 segments and it takes some self dmg after breaking 3 segments and then again after breaking the 6th (HP based) and then another instance of damage once it's fully broken (this one is based on how much damage you dealt to the shield, conversion rate unknown).
You have 25s to break the shield, or else it's going to deal massive dmg in an AoE big enough to cover the whole Abyss arena.

Once the shield is broken the Gecko is downed for about 7s, after which it will immediately spawn the radiant cocoon (the mechanic you need a healer for).
While the Cocoon is active you have -100 crit rate, -50 dmg%, -40% incoming healing and it has 70% Geo Res.
After you fully heal a character you will clear the radiant debuff on that character and you will cause the Gecko to lose its Geo RES (drops to 10%), on top of gaining buffs from clearing the debuff on that character (+15 crit rate, dmg dealt +50%)

It will redo the shield phase 50s after breaking the first one.