Requirement: 50 Total Deaths
Unlocks: Grim Reaper

Requirement: Bowman hit while < 50 HP in first 30s
Unlocks: Gunner

Requirement: Win a 1v3 using a Normal unit
Unlocks: Spearman

Requirement: Dagger wins 1v1v1: Under 30 HP Dagger must kill another
Unlocks: Ninja

Requirement: Make a Reaper kill another Reaper using its special death mark ability.
Unlocks: Guardian Angel

Requirement: 100 Total Kills
Unlocks: Zombie

Requirement: Blue, Red, and Yellow must win 3 times each.
Unlocks: Cure

Requirement: Scroll far enough past the arena until reality glitches.
Unlocks: ERroR