The Global Ability on the Relentless Basic Action card says this:
Pay 1 [mask]. Target character cannot block.
The ruling on Mystique: Raven Darkholme would suggest "target character" means all dice for a unique character. So if my opponent has 2 Storm dice fielded, I can pay 1 mask energy and neither of those dice can block.
That doesn't sound right though, so I thought I should ask for clarification on what is meant by "target character" in this case. Does it mean you should choose a die and that die can't block, or do you choose a character and none of that character's dice can block?