Story
The Beastmaster is a spirit that carved the Colosseum out of spirit as its domain, much like the Spirit did for the Spirit World. It studies "creatures like you", and created the Colosseum as a "game room", for people to enter and fight powerful enemies in their simulated areas. It awards you with Spirit Points, its own unique currency to allow you to trade with it and unlock new parts of the Colosseum. The Beastmaster also gives you tips on how to defeat each enemy in the Colosseum with the equipment it provides.
Trading
Unlike all other shops, except the Spirit, the Beastmaster has an unlimited inventory, and uses spirit points instead of money for its trades. You also cannot sell to the Beastmaster.
Boss tips
Minotaur
These beasts are fast and have dangerous Horns, but move endlessly back and forth and are easy to predict. Try keeping your distance and hitting them from behind.
Yeti
Unlike many enemies, you can't hide under Yetis to attack them from behind. Try staying on the move and sneaking in hits while avoiding its icy breath and snowballs
Bandits
Like most groups, bandits aren't that dangerous one on one, but don't let them gang up on you! Pick them off one at a time, and pay special attention to the bandit with the heavy shield, he can only be hurt from behind!
Dragon
With no ranged weapon, the Dragon's a challenge. Hit [Defend key, Space by default] to block flames with the shield or hide behind tiles until it flies back to its den, then hit it from behind as much as you can, and don't forget Attack Potions!
Wyrm Queen
This beast won't attack you - but it can only be hurt by striking its open mouth! While its brood of Wyrms are dangerous, they are a good source of Dragonblood if you need to heal.
Golemech
Beware the Golemech's eye attack - it takes time to recharge, but it is incredibly powerful. Plant and Water attacks are effective against it.
Old One
The Old One has powerful attacks and is only vulnerable when it overheats and opens up its armor. Dodge or block its attacks with the shield, then hit it when vulnerable.
Mirrows
The Shadow Cape will help you avoid being attacked by both Mirrows at once. It will make you invisible every 5 seconds, allowing you to sneakily defeat one of them. You can also use Landmines while hidden for extra damage!
Pirates
The Pirates have powerful laser weapons, but their range and speed are less than yours. Keep moving and firing, taking as few hits as possible, destroy one at a time, and they aren't that challenging.
Kraken
This monster of the deep is very hazardous. Its arms are dangerous, and while they can be blasted off at the base, they regrow quickly. Destroy and get past the arms, then fire at the eyes to defeat it.
Cultivator
The Cultivator is weak to Fire attacks. Burn it from the air where only its spores can hurt you. You will have to dodge the spores, as you don't have a lot of health for many hits.
Storm
The Storm can only be hurt by powerful Fire attacks. Beware its tornado form, it is invulnerable and dangerous during that time. Climb the ruins to burn it when vulnerable, and run when it's in tornado form.