Spiny
Anything careless enough to attack a spiny creature in melee will take damage from the defender's spines. Ranged or reaching attacks ignore this counterattack, as do spells.
Monster Version
Each time anything attacks a spiny monster in melee, there is a chance that the attacker will take Nd4 damage (Nd3 if the attacker is a monster), where "N" is the defender's spiny degree. This damage ignores EV, but is reduced by random2(AC/2).
Player Version
You can acquire the spiny trait yourself by gaining the demonspawn spiny mutation. Spiny players may hurt attackers with a probability which depends on how many levels of the spiny mutation they have, as well as the encumbrance rating of their body armour; heavier armour reduces the effectiveness of one's spines:
Spiny Damage
Spiny 1: 2d5 - AC - Encumbrance Rating/3.
Spiny 2: 2d5 or 3d5 (equal odds) - AC - Encumbrance Rating/3.
Spiny 3: 3d5 - AC - Encumbrance Rating/3.
As with monster spines, this ignores EV. However, you can only affect the first attack of any given monster per round.
Spiny Monsters
r Porcupine(3 degrees)
P Briar patch(4 degrees)
1 Hell sentinel(5 degrees)