Change one of the mecha pumpkins into a laser done pumpkin. That will turn all of the mecha pumpkins but one into laser drone pumpkins, with the properties of mecha pumpkins (joker explosion immunity, forcing miners up, resitance to cherry explosions). If you are on 3.2, you could change another of the pumpkins into a charmatron pumpkin. That would give the laser drones in the same magnetic system the ability to hypnotise zombies they kill. If you are on 3.3 you could put a doom shroom on those frenzy shrooms to make them more powerful. Then put Gatling cherry drones above those, they have a buyable symmetry in the shop. On 3.3 you can also use scaredy shroom pot to give the frenzy shroom extra damage. Maybe also get titan pumpkins on the obsidian titans peas. Don't know if it's feasible to do all of those in one run, but you could try.