I've been using mine for Greyhoof of the Beast of Legends.
1) Ice Tomb
2) Greench's Gift
Greyhoof is usually down to about 1100 when the Ice Tomb stuns him then I switch in a Clockwork Gnome
1) Build Turret
2) Metal Fist until one of them dies
Usually that does it, but sometimes I need a second Clockwork Gnome to finish the job.