After collecting all of the Tower Heart shards, take it to Queen Fay so she can repair it. After the cinematic, take the Tower Heart to the sanctuary dungeon to power it up with the shrines. After charging the Tower Heart at the first shrine, you, your minions, and the Tower Heart will fall. When you find the Tower Heart, it will be sitting on top of a gnome hole that spawns an unlimited amount of gnomes. Position all your minions next to the hole by using the guard marker and, when you have your minions where you want them, remove five minions so that you can move the Tower Heart to a safe location. When you think the Tower Heart is out of you way, put all your minions on top of the gnome hole. The gnomes will die as they jump out of the hole. Walk back to the Netherworld Gate, but do not go into the gate. This will require about twenty minutes. Note: Do not get too close to the gnome hole or else the gnomes will run past your minions and attach themselves to you.