There are fifteen Races of in Combat Monsters, each with their own Passive Ability. 
- Cyclops: All Cyclops get +2 attack each time any friendly Monster dies.
- Dwarves: All Dwarves get +2 attack each time they are attacked but not killed.
- Elementals: All Elementals get +1 attack and +1 health each time you play a spell.
- Elves: All Elves get +2 health while their controller has no other races in play.
- Golem: All Golems +3 health each time their controller plays a rune.
- Humans: All humans get +1 attack for each other friendly Monster stood next to them.
- Imps: During upkeep All Imps get +2 health instead of -1 if afflicted with flame.
- Lizards: All Lizards get +2 attack when they kill a creature.
- Minotaurs: All Minotaurs get +1 attack and +1 health each time they gain some equipment.
- Orcs: All get +1 attack for each other friendly Orc in play.
- Robots: All Robots get protection from all afflictions.
- Spectrals: Spectrals cannot be equipped, but take no damage from basic attacks with default weapons.
- Werewolves: All Werewolves get +3 health each time they kill an enemy creature.
- Zombies: All Zombies get +1 health each time any creature dies.
- Skeleton: All Skeletons start with shield+3 but get shield-1 for each equipment.
- ↑ http://www.rubicondev.com/blog/combat-monsters-multiplayers-coming/