So I dps her down to 30% for phase one, then I run back to the npc to get under the bubble for phase 2. As soon as the bubble is gone I run towards Sinestra to dps then I’m one shotted.
What am I doing wrong?
You need to kill the eggs on the sides in phase 2. Basically you damage Sinestra to burn her mana shield, she will then drain mana from the big twilight eggs on the sides, you need to kill them during this part to get into phase 3.
As for you getting 1 shot, I have no idea.
As Denona said, you are supposed to kill the eggs first. If you do not kill the eggs first it’s a wipe. During the encounter, you’ll see a prompt that talks about the eggs (I forgot the exact prompt but it looks like a raid warning). Each of the eggs on her side will normally have a debuff that looks like Arcane Torrent. When that prompt triggers, you’ll see one of the eggs without a debuff. You kill that egg and wait for the next prompt and kill the second one. After that, you’ll be able to kill Sinestra.