But I came to a dead end, so maybe someone here has a crazy idea to push this strategy to the limit

Punchbag Strategy
Here is how it goes:
The goal is to create a monster with 100% physical resist and low damage and enough damage reduction to get no damage. In other words get a punchbag that you can punch as often as you want!
Why would you do that other than fun? Because you can exploit it!
Prep Fire Heart, EM, Bear Mace and Quest Items with a Dwarf Transmuter (or any other race for that matter)
Now get to 100 HP on lvl 1 (that is the dead end, maybe someone can lower this), but its still less than Astrals 110 HP combo

Then create a wall on an empty spot next to your punchbag (3 mana), push the punchbag into it (no damage to both), but +1 mana +1 HP from the rock heart, use BLUDTOPOWA 2 times (6 HP) and repeat.
Effectively you get +5% maxHP + 1 HP on the fire heart for 2 mana (or 6HP). That means getting 100 maxHP is enough to get an endless loop! Oh and because you are a transmuter, you will get infinite CP with that, so infinite attack, infinite mana, infinite potions and so on

It pretty scummy, because you need MA for the punchbag (join, kill a spell monster, spam glyphs, get into EM and desecrate MA) and EM for the IMAWAL and Vine Form for the DR and maxhp. Optimally you have GG as your third diety for a level up + absolution spam + humility to get to 100 HP and you need the rock heart and BLUDTOPOWA...
overall its possible but not very likely. Any ideas how to lower one threshold or get an easier punchbag?^^