So I play with the provided robot, plus my companion. When I get to Mentor, the green beam always targets me, so it's only a matter of time before I die.

 

Is it supposed to be like this? (Doesn't realy make sense)

When the green beam targets you in the last phase, it's time to pop your defensive cooldowns (damage migitation, reflect, heals) and burn down Mentor with everything you've got. It's a dps race at this point, but a companion healer together with the jesus droid should be able to keep you alive even if you lack the expected dps. If you are the healer or tank you may want to respec for this fight.

 

Don't forget the heroic moment, heals and extra damage abilities is what you want now.

There are also the Unity and Sacrifice abilities you can either buy in the legacy or gain for free at Light V / Dark V

One is 50% damage reduction, the other an instant heal to full at the cost of reducing your companion to 1 HP.

Edited September 9, 2017 by Mubrak

I first did this as a level 45 marauder (bumped up to 50) and at that point I just wailed on Mentor until he went out. Never popped a DCD or anything.

 

DPS all the way and leave the healing to Mechajesus and your companion, you should be able to do it by yourself no problem.

For me the key was doing the flashpoint with the right companion so I didn't get clobbered by Mentor. There are some Force using melee companions who are very aggressive even when they are on healing stance - I took in Lana, but Jaesa and Xalek also spring to mind. Anyway, I made sure Lana was L50 influence and I had the droid, and just kept directing them (target, CTRL+1 on the enemy) to attack the cores.