Like this you can consistently kill him in ~3 minutes or so, (sometimes as low as two) with 9-12k in rewards, meaning you make somewhere between 3-5k per minute of grinding.

Also, FYI if you're ever just waiting for him to make another move, you can spam ballista bolts at him and he'll still take damage, just not much.

FYI the ideal strategy I've found is
1: wait for your apple grenade
2: wait for his first boulder and use the apple grenade OR (if it's not ready) the triple ballista
3: spawn your hero behind him to use your bow on his eyes again
4: wait 1-2 seconds
5: run up to his foot and repeatedly heavy-attack it
6: once he picks up another boulder or your hero times-out, immediately apple-grenade his eye again (note, once he starts picking up a boulder he seems to gain I-frames)
7: use the map-wipe spell to kill the golem on your door
8: start summoning troops (any ranged unit)
9: shoot eyes with another apple grenade
10: wait until your apple grenade is charged then aim for the spot between the two mushrooms on his leg, shoot the apple-grenade through his legs and set it off at the right time and you'll get another hit on his eyes
11: rinse and repeat. Your troops can handle the golems so focus on hitting him in the face and then using either your hero or more apple grenades between the legs

Thanks

alredy done

heres something I wanted to add: When you hit his eye while he is holding the rock, he will cover his eyes and hide at the back of the cave. you can summon your hero to shoot his eye near the cave. but be careful, he smashes the ground where you can shoot him 1-2 times before getting up again.

or use projectile sheild to block the big rock it bounces back and kills him