Keiss
Note: ST stand for Single Target and AoE is for Area of Effect
Note: C65 stand for crystal level 65
Assessment are based on MLB 15cp, 35cp, EX and EX+ weapons
What he do
BRV ATK
Range attack - Steals enemy's BRV
Change to 3-hit ST BRV ATK++ while Selkie Soul active
Grants party BRV based on own MAX BRV
Change to Selkie Chase (BRV) during chain attacks
Reduces target's BRV to 0 if not afflicted with Break; grants party BRV based on own MAX BRV
Debuff Fitted Enfeeblement (lowers DEF, SPD) to target after chase
HP ATK
Range attack - Expends BRV to deal HP damage
Change to HP ATK++ while Selkie Soul active - Grants party BRV based on own MAX BRV + 2-hit ST BRV + HP ATK
Change to Selkie Chase (HP) during chain attacks
Grants party BRV based on own MAX BRV; HP attack
Debuff Fitted Enfeeblement (lowers DEF, SPD) to target after chase
Skill 1  (Selkie Throw)
Range attack - 4-hit ST BRV + HP ATK
Deals 50% HP damage to non-targets
Buff Selkie Soul (raises party's MAX BRV, ATK, critical hit rate) and ATK Up II (raises ATK) to self
Skill 2  (Hero Support)
Range attack - 6-hit ST BRV + HP ATK
Grants party BRV based on HP damage dealt
Selected ally: 1 turn Smash Support
Moves next turn to after selected ally
EX+ (3/3) Skill  (Sky High)
Range attack - 6-hit AoE BRV + HP ATK x 2
Deals proportionate HP damage to each target
Delays all targets 1 turn
Buff At the Ready (raises party's HP damage dealt in chain attacks; lowers all enemies' SPD ) to self
What can he provide
Turn manipulation, delay with his EX+ and let any character in the party become a launcher.His c65 marginally raises party's ATK for 3 turns, Hero Support use +1 after use (with upper limit). He has Mighty Critical Hit and Back Attack in his passive abilites. His C68 slightly boosts party's MAX BRV. He has a A sphere: After joining in chain attack: Raises ATK by 10% for 8 turns
What can he be
Support on BRV, secondary damage dealer.
Overall thought
He is a support character with good damage. He can delay, turn anyone in the party into a launcher, provides BRV during chain ATK, BRV ATK, HP ATK and skill 2. He best tag with a tank as he has Back ATK (perform better when not targeted), healer as he cannot self HP regen. He does debuff.