Most VIT pallies die instantly, with Creos and Thana Cards, but with LK Card they're pretty much invincible, but they can still be hitlocked and be AD-ed to death.
High Rate Servers = No delay + at least 2 max stats + 196 ASPD = Star Gladiator + Miracle + FSK = Instant OP
I suggest make Thanatos Card take 100SP per hit and reduce GTB card to 50%-70% than 100%. And don't put OP customs.
I am assuming most people use different builds and strategies. I played HR servers a lot with minor modifications on cards, and it's completely fine. You can counter every class with something. Unless people started whining about people they can't kill, they'll start suggesting to change things, be very wary.