The Monster function unlocks at Level 70. It buffs your team and has its own active ability, but it has no basic attack and can't be attacked. You can have one monster active at a time.
Monsters
They require 
Monster Souls to level up the active ability.
They require 
Chaos Stones to level up Auras.
It costs 245,558,140 
Gold, 133,177 Monster Souls and 23,033 Chaos Stones to fully max out a monster.
Wolf
Requires 240 Monster Souls to activate.
When you team up with wolf a blue glowing border will appear around your teams hero icons.
- MAX Stats
- Violent Bite - Deals 265551 damage against 4 random enemies and bleeds them, dealing and extra 246482 damage per round for 3 rounds. Meanwhile, increases 4 random allies 65% of damage against bleeding targets for 2 rounds.
- Heroes that work well with this monster
- Any hero that has a bleed ability.
Horus, Das Moge Xia, Mirage, Blood Blade, Cthugha, Queen (Note: Queen does not get a bleed until 10- star) - Expand below to view Tier information
Tier 1
Tier 1 caps at level 30 and is your starting tier with the monster aura Blade Teeth
- Aura Stats at max
- Increase team HP 15855, Attack 1164
- Cost to max this tier
- 7.8K Monster Souls and 3.7M Gold
- Cost to max your Tier 1 monster aura
- 2.1K Chaos Stones and 10.6M Gold
Tier 2
Tier 2 caps at level 60 and activates the monster aura Swallow the sunlight
- Aura Stats at max
- Increase team HP 31710, Attack 2095 and Armour break 20%
- Cost to max this tier
- 24.5K Monster Souls and 13.0M Gold
- Cost to max your Tier 2 monster aura
- 4.6K Chaos Stones and 26.4M Gold
Tier 3
Tier 3 caps at level 90 and activates the monster aura Call of the Wild
- Aura Stats at max
- Increase team HP 52850, Attack 3491 and Precision 10%
- Cost to max this tier
- 41.0K Monster Souls and 26.3M Gold
- Cost to max your Tier 3 monster aura
- 7.0K Chaos Stones and 47.6M Gold
Tier 4
Tier 4 caps at level 120 and activates the last monster aura Curse of the devil wolf. This is the current highest level for monsters.
- Aura Stats at max
- Increase team HP 95130, Attack 4655 and Speed 40.
- Cost to max this tier
To level your wolf from level 90 to level 120(old max level) will cost the following
- 59.9K Monster Souls and 44.8M Gold
To level your wolf from level 120 to current monster max level of 18 will cost the following
- 542K Monster Souls and 303M Gold
- To max your Tier 4 monster aura
- 9.3K Chaos Stones and 72.2M Gold
- To max your Tier 4 monster rune (these unlock after you max your auras)
- 121K Chaos Stones and 248M Gold
Owl
Requires 240 Monster Souls to activate.
Deer
Requires 320 Monster Souls to activate.
Fox
Requires 320 Monster Souls to activate.
Dragon
Requires 410 Monster Souls to activate.
Snake
Requires 410 Monster Souls to activate.
Boulder Golem (Rock)
Requires 410 Monster Souls to activate.
Ice Golem (Ice)
Requires 410 Monster Souls to activate.
Phoenix
Requires 410 Monster Souls to activate.