How many times were you bouncing the balls? I think we did 5, 3, 3, 3 without any issue. As long your tank pop CD when the stack are getting high (raid CD are also welcome), raid damage should be manageable with 3 heals.
As for the balls bouncing, we used the positioning suggested here and never had any trouble.
Spoiler: show
Essentially, melee are stacked on tanks and face the range. As soon as the balls spawn, tank turn the boss 180degree and the balls should automatically ping pong between both group with little to no movement. After the 5th bounce on range, every melees run through the boss (stack on the tank) and the ball should hit the boss.
We fucked up once, but I had no issue moving the boss around to "catch" the ball. Every other time, it was just a matter of melee moving out of the way after the correct number of bounces. This fight was about as close to "tank and spank" as it can get.
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