Wish I had access to the musketeer files so I could use them for modding alas I missed out on the kickstarter campaign
Aside from that more ability ideas
Flank\Death from above: High crit chance nuke and or bonus damage vs marked
Mark Prey: Mark target increases accuracy/crit on target
Also not sure how difficult it would be but you could make it so it gives an item similar to the houndmasters snack that boosts damage
Necromancer Class mod
http://www.nexusmods.com/darkestdungeon/mods/137/?