If you have self heals just stand in tendrils until you collect 9+ bloods. Pull an amalg on top of them while moving left and right on spine (to reset the roll cast) and then kill amalg/tendon. Rinse and repeat, GG.
The only classes its a bit more difficult on is classes without passive healing or on demand healing. If you have one of those classes, the strat is simply collect 9 bloods while running left and right periodically to reset roll timer instead of just standing in the tendril and taking the damage and not rolling.