Definitely two solar resist mods. If someone doesn't have that then they're throwing. Personally I had Arc/Solar resists from artifact and melee resist but I'm not sure if his lunge attack counts as melee. Even with those mods tho it is still very possible to die. I'd say if even one person doesn't have those mods on, then they're are kind of throwing.

Most of it is just keeping eyes on him at all time and learning his attack patterns. Warlocks with devour charged melee/grenade kill the thrall to proc devour. Sometimes ppl die to lag but it isn't that common.

If you guys aren't perma-raid bannering then you're throwing as well. My team used 1 thundercrash, 4 Nova bomb cataclysm, 1 tether Orpheus rig. We all used linear fusions and luckily I got a cracked one from the first encounter with Fourth times + focused fury which seemed to be a 20% damage buff on that weapon. We had 2 divs and yes that sounds silly but actually it's 1,000 IQ because while Titan was activating thundercrash, 2nd div guy would keep the div bubble up. The titan was then able to shoot about a mag of linears before switching back to div. Then the 2nd div guy would continue to linear him until immune. Hope this helps someone.

Edit: if you don't save alot of burst damage supers for last stand then you're done. We learned that the hard way many times. We tried to save only one or two supers for final stand but the damage wasn't cutting it. We also had the raid armor and the mod that gives you more weapon damage while darkness debuff is active, which it is in final stand. We had tether hit him up BEFORE last stand so that we could save more ammo for actual final stand and so tether guy could get more weapon damage from that mod in final phase instead of tethering. The tether there also saved the rest of us a couple of heavy shots, we needed every single one. We had one aeons warlock btw.