Thanks for all the feedback. We had our first pulls yesterday, went with green -> yellow -> purple. We also went a little on the safe side and 4-healed it. We killed it and even though our kill was quite slow (5m41s), it felt rather easy. The only hard part using this strat is indeed the last pool. Empowered waves + pound, then empowered runs -> dragging hands -> pound. After that the boss falls over.

I can however imagine purple first being easy, as the only hard part about purple is having all the empowered abilities together with empowered waves.