well tbf fight design also has alot to play here as well at least for bosses whens the last time you used esuna? exactly, outside of the once in a blue moon reminder of wait a minute i have this skill? you could just remove it just like the sleep skills outside of the one SHB role quest. imagine a boss similar to nidhogg EX where it'd be beneficial to sleep the middle mob and keep it slept until the two side minibosses were taken care of. in this scenario it would be using it's vuln up at faster intervals out the gate. so you have to keep it CCed to prevent the damage from getting to a point that tanks even kitchen sinking and swapping will die.

or bring back multiple ways to deal with each fight. like if you needed the extra time for your tanks to double weave their opener you can prepull cast aquachains (just an example) on boss to apply a casting bar slow effect to the boss. letting the tanks get an extra GCD and 2 more weaves in before the buster or if the mechanic would (actually) force melee out you can use it then to give your melees more uptime. let's even take this a step further and think about how each healer could this.

WHM would just be a quick easy GCD that just costs a lily (no feeding the blood lilly as that would incentivize it to be used on CD) (WHM is the noob/new player healer so it has the simplest solution ofc)

AST could use a seal to apply the efffect (allowing you to reroll seals in other ways incase you get screwed RNG wise as well)

SCH could spend 50 gauge to have their fairy do respective abilities (selene would apply the cast bar slow eos would apply a group wide buff seraph would of course do both and prolly apply shields as well maybe)

SGE would spend an toxicon stack to apply the debuff (this would hopefully happen next to you being able to trade addersgall for toxicon stacks so you can make up for the loss potentially)

since i can almost guarantee the melee getting more damage in, at the cost of your own damage would be higher overall. it would make it worth it in the long run. but we all know fights are now damage or nothing essentially. heaven forbid we have unique ways to tackle fights anymore besides how braindead can we make this mechanic?

also can i just sneak in rq how much i hate eukrasia and kardia and how poorly they were implemented? a 1 sec GCD to access your alternate abilities instead of something more interesting and thought provoking like having to use an addersgall or toxicon stack to access your alternate abilities. or hell just make it an oGCD so you actually have to think about weaving it. also why just like three GCD abilities? why not like 2 oGCDs as well?

kardia not even having an option to be turned into a party wide effect where each damaging ability used applies a small shield to the group for 15s for example. hell i'd get rid of pepsis for that. no offense to pepsis it's just way too niche to be relevant once you actually know the fights. but it still does have it's uses and could see even more with this kardia change so eh idk