Abomination can deal some great damage in beast form without relying on crits, due to self-buffs and high base damage. His base damage is 7-14, which is higher than any class except the leper, equivalent base damage to the leper, but with better base accuracy than the leper. He has a camping skill that can buff his damage by 25% until next camp, his transform buffs him by an additional 10%, his aoe rake attack gains a self-buff on use, adding +15% rake damage at level 1, which can stack up to 3 times giving 45% damage total, negating rake's penalty of -40% damage. So you can have an aoe attack with good accuracy and high damage to mow through the front two enemy positions. Fully buffed rake would have +5% base damage at level 1, with +10% damage from transforming and possibly an additional +25% damage from camping. I like bringing a plague doctor with emboldening vapours (+25% damage +3 speed at lvl1) to keep buffing him further.
His rage skill lets him attack any of the front 3 enemy positions, dealing good single target damage without having the "buildup" period of stacking buffs that rake requires to reach max dps. The only target he can't hit in beast form is the enemy in the very back.
I find him to be a
really reliable source of damage. No worrying about crits, has good accuracy, has good ability to deal damage to either crowds or single targets.
I happened to get a couple good trinkets for the class too, a green lock grants +15% protection for tanking, and an orange lock that lowers the stress damage inflicted on both himself and the party from transforming. Makes him all around great at everything I need him for, tanking and dealing damage in beast mode.
Also the transformation animation and the animations for beast form look pretty cool.
I haven't gotten into the higher difficulty missions, but all the green missions I've taken him on go really smoothly, and I killed both the siren in the cove (really easily) and the bandit 8-pounder in the weald with two abominations acting as the damage dealers and tanks while a jester and plague doctor served as support.
I don't typically use a cutist. For healing in a party with the abomination I usually use either a plague doctor or arbalest.