Dave, Fist of Odin
I give the white lotus to the dead girl, and throw the weed killer on Vrill. Let me know what happens - I'd like to actually get some inside him, but I figure straight-up combat's not the way to go here.
If nothing happens, I eat it. Two saves, BR15, BR 12 - makes 'em both.
Then, if things aren't resolved, I pour some plant-growth potion around, some on R-B, some on the hedges.
That's - what. Three, four rounds? Rob, I'll let you make the call how long it takes. Let me know if you want any rolls, or clarification, but that's what I'm doing, so I'm cool with just making it happen.