my understanding is that it raises base agi stat by 25% (at max) vs haste raising ct accumulation by 50%. haste seems like it will always be better for pure turn speed but increasing base agility might also buff other things like evasion or damage of certain units/skills.
They also stack, I often use haste on someone using lucia tmr and usually get 2/3 shots off before an enemy tank moves the second time
Anonymous
I dont know if its a bug but this skill use more TP than in the description. After my ayaka use this 3 times, her TP is too low to cast other spells than cure.