Carth is a little lackluster right at this moment, I think the HK rework will finish it. Another source of DoT, plus deathmark maybe, and maybe some group buff on basic, like accuracy up and potency up or something.
Leading mission, Zaalbar, Canderous, & HK, you'd have 4 sources of DoT (5 with Mission's zeta). With all those assists, you get even more DoTs. This team thrives on them. Then, after you kill one enemy, HK applies deathmark to another, and you start rolling.
That said, the real MVP DoT team will be Zader with Mission, Zaalbar, Carth, and Wampa. Maybe sub in Canderous for mission.