Slime kills quickblade, pull is irrelevant, narrate whatever you want.
A note about Mertes's and Alessa's turns:
If Mertes's turn is first, then Dragonshield 2's readied action (charge any enemy who falls from the walkway) triggers. Mertes eats an attack, with CA since he's Prone, (I haven't rolled it yet) and the DS is safe from the buffeting wave.
If we rearrange the turns so that Alessa's is first, then Mertes's and Alessa's actions go off without a hitch (DS2's readied action is lost due to being Prone). I also happen to think this is cooler. It makes the fight easier on you guys, but I suspect you need the help.
Dragonshield 1's readied action was to charge whoever killed the Quickblade. As he was Prone when that happened, the action is lost.