Healer =! Cleric
I'm a Healer + nothing offensive. Healers also don't have the armour of a cleric. Clerics and battlemages stand supreme as the two best multiclasser mass killers in the game.
Healer/Ranger/Druid and I'm currently levelling up Spiritist (77 now). I have no offensive power in Healer mode at all, and I can kill most anything one on one on the satyr islands without stunning it to death (blue vexes kill me unless I hit them with 2 stuns). I have no techs for melee weapons on my armour or jewlery, and the same base skill as a dragon. I have no melee abilities except Crush and Powerstyle. If I can do it than so can any level 100 dragon in tier IV unteched scales. They have more strength, same weapon skill, more health, more armour, and more specials. You just can't jump in and rush a mob head on. You'll die if you do that. So would I (and I do). You have to be *smart* about how you attack powerful mobs. That's the key. Though I will say, being a Ranger as well as a Healer it is easier to kill the darned things with a crossbow than with a mace.