Battle Heimdall

Remember the Spartan teachings

Battle Níðhögg

Battle the Mysterious Valkyrie

Upgrade one piece of armor

Battle the God of Thunder

Earn at least one Star in Co-op.

Kill three Enemies with the Riot Shield in the Campaign or in Co-op.

Kill everyone in a time period and escape.

Complete 'Lost in Transmission.'

Kill the Garbage Collector and acquire the Fugue slab.

While playing as Colt, cause someone to fall to their death.

Infuse a Slab.