I should have 300 mana right now. (Warriors had 300 HP).
Option 1. I have just enough mana for two Invisibility spells + I can drink some potions, but that takes three turns. The zombie might destroy the shop (I don't remember what was there about the torches) or clean up, but I'm not sure if it can handle that. Advantages: while I'm casting Invisibility, you'll have three turns to COLLECT LOOT. Disadvantages: we'll probably get caught again.
Option 2. We grab the invisible elf or make another elf invisible and leave with what we have. We have a top-tier crossbow, sword, two-handed weapon, and maybe something else. The options with the zombie are the same. Advantages: there's a chance to escape. Disadvantages: NOT MUCH LOOT.
Option 3. Instead of Invisibility, I create a zombie army while the rest collect loot. This army can be used to completely destroy the shop, so the visitors who arrive later will think it was their doing. Then we can remove the phantoms. Advantages: see option 1. Disadvantages: see option 1.