You have no idea what the ugly thing is or where it might have originated from.
Evistro (Carnage Demon)
Medium Elemental Magical Beast (Demon)
Rituals known to demon-worshiping cultists and
certain depraved wizards can summon evistros to the world.
However, evistros are notoriously difficult to control—usually,
the best their summoner can accomplish is to send them out
to wreak havoc. Sometimes, though, they turn on their summoner
before extending their rampage.
Evistro (Carnage Demon)
Medium Elemental Magical Beast (Demon)
Claws (standard; at-will)
+9 vs. AC; 1d12 + 5 damage.
Destructive Bite (minor; at-will)
Bloodied target only; +8 vs. AC; 1d6 + 5 damage.
Carnage
The carnage demon gains a +1 bonus to melee attacks if it has
one or more allies adjacent to its target (+3 if one of these allies
is another carnage demon). This bonus stacks with combat
advantage.
Rituals known to demon-worshiping cultists and
certain depraved wizards can summon evistros to the world.
However, evistros are notoriously difficult to control—usually,
the best their summoner can accomplish is to send them out
to wreak havoc. Sometimes, though, they turn on their summoner
before extending their rampage.