Gamorrean Guard in raids

So every where I have looked I have run into people running gamorrean guard down. I started using a level 60, 5*, vi gear, and level 3 abilities maybe level 4 basic ability with phasma (lead), qui gon, gs, and admiral ackbar for phase one and switched lumin or jc for rancor. All other characters except the guard are level 71-73, 7 star, 5-7 abilities and 7 or 8 gear. Gaurd is doing 100k-130k damage when the rest of the team is only pulling 80k to 100k. typically I have around 6-10 that tick for 1800 each but when in regular combat he only deals 120-130 damage per tick. What is this percent that dots are suppose to function on? Since this is within 5* raid does he preform this strongly in 6* or 7* raids? I had unlocked him and starred him because he looked cool and about abandoned him for Rey.