Healer is surely helpful. First try and I got gold medal on 2nd map (exactly 10 out of raiders), having 2 goblin raides, 1 shield goblni, 1 mammoth turtle and 1 healer
http://www.thegamehomepage.com/play/scriball/LolQuest/2aaqp~1ddhdidjdlddehejeledfhfjflfdghgjglgdhehfhhhihjhlhmhnh~2edfdmdndeefeiemeneefffifmfnfegfgigmgng/ - lol my level.