kingqdo116,228 29 May 2017 30 May 2017
Combine with achievement "general":
Any hero (simple unit).
You need the spell "heal" for this one. take an easy mission (maybe first one?) and only hire one hero (simple unit), let the main hero(es) stay and dont move.
Now heal this one unit till he killed enough. Don't let him destroy the spawn thing, just drag and drop him back.