Unit Abilities

Auras

 * Aura of Courage - in battle this unit provides +1 bonus to to-hit rolls to all friendly units.
 * Aura of Heroism - in battle this unit provides +1 bonus to to-hit rolls, Armor Class, and saving throws to all friendly units.
 * Aura of Resistance - in battle this unit provides +5 spell resistance to all friendly units.
 * Aura of Resolve - in battle this unit provides +1 saving throws to all friendly units.
 * Shielding Aura - in battle this unit provides +1 bonus to to-hit rolls, Armor Class, and saving throws to all friendly units.

Attack-Oriented

 * Bleeding Attack - unit's attack cause bleeding for 2 turns.
 * Charge - if unit moves before melee attack, it strikes first and receives +2 bonus to to-hit roll and +2 damage bonus for this attack.
 * Cursing Touch - unit's attacks inflict Cursed status (-2 to to-hit rolls and damage). Bless spell prevents/dispels this status.
 * Drain Life - heal for 50% of damage dealt to Living or Elemental enemies.
 * Ethereal - attacks ignore opponent's armor bonus to Armor Class (are more likely to hit).
 * First Strike - unit strikes before the enemy.
 * Long Reach - unit can attack Flying units in melee normally, with no penalties.
 * Mana Drain - unit drains mana from attacked enemy.
 * Point Blank Shot - +1 to-hit and damage of mundane ranged attack on enemy within 5 tiles.
 * Reach Weapons - unit can attack Flying units in melee normally, but with -2 to-hit penalty.
 * Siege Engine - unit can attack and damage walls using ranged attack.
 * Sneak Attack - all attacks made while invisible should be critical hits. I don't think that means 100% critical chance.
 * Stoning Gaze - unit has gaze attack capable of turning enemies to stone.
 * Thrown Weapons - unit has Thrown attack, which happens before normal melee attack.
 * Wall Crusher - unit can attack and damage walls using melee attack

Movement

 * Flying - unit flies - it can be attacked in melee only by units with Long Reach, Reach Weapons, or Flying. This does not protect from thrown and gaze attacks. Unit can fly everywhere on the world map without terrain penalties.
 * Forester - unit and its army ignore movement penalty of forest tiles.
 * Levitation - unit can move on any land tile with no move penalties, but does not benefit from roads.
 * Mountaineer - unit and its army ignore movement penalty of mountain tiles.
 * Merging - unit can instantly move to any tile on the battlefield.
 * Pathfinding - unit and its army can move through any land tile with no terrain penalties.
 * Swampdweller - unit and its army ignore movement penalty of swamp tiles.
 * Teleporting - unit can instantly move to any tile on the battlefield.

Defences

 * Clear Mind - unit is immune to mind-affecting spells.
 * Death Ward - immunity to Death effects.
 * Divine Grace - add Charisma bonus to all saving throw. Exact bonus will vary.
 * Fear - opponents need to pass will saving throw to attack this unit in melee.
 * Evasion - if a spell allows reflex saving throw for half damage, this unit will negate all damage on successful saving throw.
 * Flying - unit flies - it can be attacked in melee only by units with Long Reach, Reach Weapons, or Flying. This does not protect from thrown and gaze attacks. Unit can fly everywhere on the world map without terrain penalties.
 * Great Fortitude - +3 to Fortitude saving throws.
 * Illusion Immunity - unit can see invisible enemies, and attacks will never ignore this unit's armor bonus to Armor Class.
 * Improved Evasion - if a spell allows reflex saving throw for half damage, this unit will negate all damage on successful saving throw, and receive half damage on failed saving throw.
 * Invisibility - unit is invisible unless it attacked recently.
 * Iron Will - +3 to Will saving throws.
 * Lightning Reflex - +3 to Reflex saving throws.
 * Missile Immunity - unit is immune to mundane ranged attacks (even if using enchanted weapons).
 * Negate First Strike - unit negates First Strike ability and charge's ability to grant First Strike when attacking after moving.
 * Poison Immunity - unit is immune to poison.
 * Regeneration - each combat turn this unit regains 10% of one figure's max HP,
 * Sneak - unit can become invisible.
 * Stoning Immunity - unit can not be turned to stone by Stoning Gaze and similar effects.

Other

 * Caster - unit is capable of casting some battle spells using it's own mana pool.
 * Create Undead - units killed by this unit have a chance to come back as undead under their killer's control after combat.
 * Raiding - unit increases gold received when razing cities.

Ammo Resupply and Mana Resupply abilities are available only to city wall improvements.

Type Abilities
Those abilities are either flags to check if some effects should affect this unit, or grant unit set of immunities and dictate how Positive and Negative energy affects this unit.

True type abilities

 * Living - Positive energy heals, Negative energy harms this unit.
 * Elemental - Positive energy heals, Negative energy harms this unit. Unit is immune to Mind-affecting effects, Critical hits, poison and sneak attacks.
 * Construct - Positive and Negative energy does not affect this unit. unit is immune to Mind-affecting and Death effects, poison, critical hits and Gaze attacks (this may not include either Stoning or Doom Gaze). Unit can not be resurrected or raised as undead.
 * Undead - Negative energy heals, Positive energy harms this unit. Unit is immune to Mind-affecting and Death effects, Critical hits, poison and sneak attacks

Flag abilities

 * Summoned - granted to any unit summoned using a spell. Defenders, Roamers, and armies acquired as rewards from world features or bought at inns do not have this ability.
 * Fire Type - probably granted by chaos channels.

Magic Abilities

 * Air Circle - hero has access to some battle spells from Air Circle.
 * Augmentation Circle - hero has access to some battle spells from Augmentation Circle.
 * Biomancy Circle - hero has access to some battle spells from Biomancy Circle.
 * Death Circle - hero has access to some battle spells from Death Circle.
 * Destruction Circle - hero has access to some battle spells from Destruction Circle.
 * Enchanter - hero's spells receive +1 bonus to saving throw Difficulty Class. Can be taken more than once.
 * Evoker - hero's direct damage spells deal +10% damage. Can be taken more than once.
 * Fire Circle - hero has access to some battle spells from Fire Circle.
 * Focuser - hero gains +10 to max mana.
 * Life Circle - hero has access to some battle spells from Life Circle.
 * Mentalism Circle - hero has access to some battle spells from Mentalism Circle.
 * Protection Circle - hero has access to some battle spells from Protection Circle.
 * Spell Penetration - +3 to rolls to overcome spell resistance.
 * Summoner - increases level of units summoned by hero by 1. May have problems when summoning undead (they do not get summoned with full HP). Can be taken more than once.
 * Summoning Circle - hero has access to some battle spells from Summoning Circle.
 * Water Circle - hero has access to some battle spells from Water Circle.

Ranged Magical Attack

 * Auramancer - unit's magical ranged damage deals +1d6 lightning damage. Can be taken more than once.
 * Cryomancer - unit's magical ranged damage deals +1d6 cold damage. Can be taken more than once.
 * Geomancer - unit's magical ranged damage deals +1d6 acid damage. Can be taken more than once.
 * Pyromancer - unit's magical ranged damage deals +1d6 fire damage. Can be taken more than once.
 * Warlock - unit's ranged magical attacks ignore armor bonus to Armor Class (are more likely to hit),

Mundane Ranged Attack

 * Far Shot - reduces range increments by 50%. To-hit penalty for normal ranged attacks is calculated by comparing distance to target with ranged increment.
 * Sharpshooter - +2 to-hit and damage of normal ranged attacks. Can be taken more than once.
 * Sniper - +2 to hit and doubled critical chance when using mundane ranged attacks.

Melee Attack

 * Assassin - critical hit damage multiplier is increased by 1. Can be taken more than once.
 * Blademaster - hero gains +2 to Melee to-hit rolls. Can be taken more than once.
 * Dual Wielding - reduces to-hit penalties for wearing 2 weapons to - 2 to-hit with each weapon.
 * Improved Criticals - increases threat range (or chance) of critical hit. Each time it is chosen, threat range is increased by 1.
 * Mauler - hero's Melee attacks get -1 penalty to-hit, but deal +3 damage. Can be taken more than once.

Other Abilities

 * Acrobat - successful reflex saving throw will prevent incoming attack of opportunity when leaving opponent's melee range.
 * Armsmaster - each unit in hero's army gets 50 exp points each turn.
 * Healer - units in hero's army heal faster.
 * Legendary - increases Sorcerer Lords Fame by 5. Can be taken more than once.
 * Noble - negates hero's upkeep cost, and contributes additional 5 gold to your treasury each turn.
 * Random Ability - hero gets random ability from abilities available to his Hero Class.
 * Sage - increases Sorcerer Lord's research points by 5. Can be taken more than once.
 * Toughness - +1HP per level