For the many of us who don't have zeus yet, here's my more modest deck for the fire panzer win ...
ldr: Holy Priestess (6*)
Snake Spirit (7*)
Master of the Light (8*)
Gaea the Earth Goddess (8*)
Bahamut (7*)
guest ldr: Cyclops Chief (7*)
12.1K hp was barely enough (rnd 5 hits for a shade under 12K)
and yes, it took forever to take boss down (~75 minutes), but multi-tasking makes the time fly
PS: I got my fire panzer on a run where I had already found 5 brown chests. The gold chest was the ending bonus box!