Battle Roles are not an official mechanic, but they do allow for better character choices, when attempting to balance a party.
ROLE(S): What the Hero brings to the table in terms of party composition. This includes Abilities, Actions, and Potions. The roles I can think of (and I'm not an all-seeing seer so if you can think of one I'll add it) are:
AOE: Can deal damage to more than one square at a time. Wave, Sweep, Cross, Lance... all the Area Effects
BLASTER: Capable of high damage rolls against a single target and/or Massive Damage, such as the Riftling Rogue's Backstab. Counter-example (not a blaster!) would be the Hexcast Sorcereress, who without equipment doesn't deal a lot of blasting damage - she's a debuffer.
BUFFER: Can enhance a Hero's rolls or give some Ability that is valuable. The Ember Mage's Fire Water, for example, gives +1B and Fire; the Barbarian's Backlash potion is just downright nasty when thrown at the right target.
CONTROLLER: Can dictate enemy and friendly movement with Actions and Potions. Compel, Push, and other Control Effects
DEBUFFER: Can impair a Consul monster's rolls or Actions, typically with status effects or Auras. Obviously the Hexcast Sorceress is queen debuffer.
HEALER: Can create a Heal effect by means other than the Bandage Action. Emergency Potions rank higher than Actions, obviously, but any healing is noted. Note: Bandage is no longer available in SDE 2.0.
TANK: Can survive above average damage either with increased wounds, defense, or other mechanic. Block hallways, and draw agro/generate Wrath. Abilities like Tough, high Armor, immunity to status effects, and 6+ Hearts all lend themselves to Tanking, as does (potentially) having a large base occupying 4 squares instead of 1.
THIEF: Can open chests or has other abilities which enhance a party's chance to get good equipment. Luck, high DEX, 7+ Movement, and other variables.
Other Terms[]
These are names of tropes that explain a character for better or worst.
Glass Cannon: they can dish it out, but they can't take it. The Glass Cannon is characterized by insane attack power coupled with pathetic defensive ability.
Stone Wall: Can take it, but can't dish it out. these are Tanks with weak attacks.
Mighty Glacier: sacrificing any speed for the pure crushing power. a Tank without movement
OP(Over Powered Character): for the most part this is Candy & Cola as a mascot character it's expected.