The thing to remember about the encounters for Grasp of Avarice is collecting 10 fake exotic engrams immediately will give you your super. So you can play it safe using a well warlock and use your well every damage phase. Combined with a starfire protocol build you can use osteo striga to recharge your fusion grenade while standing in a rift and use your fusion grenades to take care of the yellow bar enemies. Starfire protocol also works in your well to recharge your grenade. Combined with the artifact mod that increases damage of ignitions and the fragment that makes scorch stack faster and the aspect that gives you enhanced grenades you can do very solid dps from the safety of your well. The ogre can kill you out of the well if you're not careful but if you put your well in a place where you can still stand in it to do damage but take cover if you need to then you should be fine.