Critical Hit X: A cumulative ability triggered during the pending damage POP that means, "If you rolled at least one natural six with this unit's attack dice, this unit does X more damage for this attack." Only one natural "6" counts in the attack roll after re-rolls. If a unit gets the Critical Hit ability after you roll attack dice, it's too late to affect the damage. Accuracy can't increase the die roll to a natural "6". However, you or your opponent may use an effect to re-roll dice to affect the number of natural sixes. (You only count the six, if any, from the roll used for the attack.) Critical Hit applies only to dice rolled for an attack, not to dice rolls for abilities like Retaliate.
Ion Cannon
Ion Cannon X: A cumulative, static ability that means, "This unit may attack a unit in the Space arena instead of the Ground arena, using X power plus any other effects." You choose whether to use Ion Cannon to attack a unit in the Space arena or to make a normal attack in the Ground arena. You can’t attack a unit in the Ground arena using Ion Cannon. Power changes affect Ion Cannon.