Frostguard is a legendary relic that grows with the hero, unlocking power by performing heroic acts fighting Giants or other Huge creatures, or defending what you love against impossible odds. The nature of the unlocked power should match the Deed, but might include: increasing the extra die size, letting the blade glow like a torch, Rousing the Storm's Fury to let it flare with cold dealing additional damage until the end of your next turn (action to activate, 1/encounter), or inflicting Slowed on a crit/hit.