This is quite interesting. So after using 2hr ability(which may share recast timer with old 2hr, although not confirmed yet), COR gets access to 3rd buff slot.
Personally I've been wondering if 3rd buff slot has ZOMG awesome use for this job, to sacrifice 2hr and extra time to do the buff. BRD having extra buff slot is certainly nice, especially in legion, when all sorts of songs are needed, attack+acc, and sometimes Scherzo. But COR pretty much only has chaos that really make or break, 3rd buff slot kinda meh unless acc is an issue after acc song was used. Not to mention doing 3 roll for ppl takes incredibly huge amount of time to execute unless already have No.11 up.
Atm Chaos+DA occupied 2 DD roll in VW/legion. Occasionally switch DA to hunters on some legion mobs. So with 3 buff slot, Chaos+DA+hunter if acc uncap with acc song, Chaos+DA+crit if acc capped and there are Ukon WAR, VS MNK in pt.
But if pt has no Ukon WAR, VS MNK? Like last legion run, DD pt setup was DRK DRK SAM RNG relic MNK. Crit-hit roll doesn't help a ton when nobody in ally using crit-hit WS, nor regain in capped haste situations with embrava. In such pt setup, no matter what roll is 3rd roll, the benefit and output increase is very small.
As for mage pt, my mage roll is pretty much reduced to fast cast+macc roll in legion for SCHs. Maybe can toss an evokers....but it's incredibly unnecessary when mages doesn't have much MP issue and evokers so weak.
As for myself, probably wizards(or chaos depending on which WS I use)+tact+snap shot roll is the best, change snapshot or tact to hunters in legion.
According to the description, I'm not sure if this 2hr can give 3rd roll in set amount of time, or can only use once then effect will be gone. Either way if it shares 2hr recast time with wild card, it's gonna be fun to decide which 2hr to use over another.