Aliens...
	Arena Challenges...

Perform the following to unlock the aliens.

Alien	How to unlock
Aerodactyle	Complete Level 2: Mess Hall Mashup.
Big Chill	Complete Level 3: Welcome to Erf.
Bullfrag	Complete Level 2: Mess Hall Mashup.
Cannonbolt	Complete Level 5: Core of the Problem.
Gravattack	Complete Level 4: Underground and Beyond.
Swampfire	Complete Level 1: Stow Away.
XLR8	Complete Level 4: Underground and Beyond.

Perform the following to unlock the challenges.

Challenge	How to unlock
Attrition	Obtain Arena Token in Level 2: Mess Hall Mashup.
Big Hits	Obtain Arena Token in Level 4: Undertown and Beyond.
Magnet	Obtain Arena Token in Level 1: Stow Away.
Malfunction	Obtain Arena Token in Level 5: Core of the Problem.
No Time for Heath	Obtain Arena Token in Level 3: Welcome to Erf.
Sale on Turrets	Obtain Arena Token in Level 6: No Time for Sightseeing.