It took me 60 turns, but when i saw that summoned units doesnt effect lds cap i decided to see how far will it go. Got bored around 60-65 turn, still hilarious summon for 800k lds and over 1 milion dmg

, and . But as said warrior would get even higher numbers since his starting lds is highter. Same thing happen with illusion on ghosts on 3rd lvl it lasts 5 turns with high enough int and kid_charna. When they go over lds limit you still keep control on them.
Any idea about phoenix spell ? When both you and enemy hero cast it ?