Life Surge either on fourth tier with Impulse Rush buff or save it for the following Full Thrust. The enemy should ideally be dead after your CT combo finishes. If it'll only last 1-2 more hits, your best bet is ID>Dis, but if it'll last longer (and assuming it hasn't purified away all your debuffs) you'd wanna follow with FT combo. It's all a judgment call you gotta decide on the fly. You always wanna lead with CT, though, especially if Impulse Rush is ready, and especially if your rdps is BRD/MCH so that their finishing heavy hitters get an additional 10% boost.
Also be sure to not use any damaging off-gcd hits until Disembowel is applied. Load up all your biggest burst at the end, between CT>4th and then after the 4th. Unlike in PvE, it's okay to delay GCDs in PvP if it means hitting with harder skills. After the 4th hit, your next shot will be 180 potency at best - load that space with skills that do more than 180 potency, instead.
