A vehicle or droid trooper unit that suffers wounds after defending against an attack that included a weapon with the Ion X keyword gains X ion tokens.At the start of a unit’s activation, roll one white defense die for every ion token that unit has. If any blank results are rolled, that unit performs one fewer action during its activation. At the end of a unit’s activation, it removes any ion tokens that it has.If an attack pool includes the Ion X keyword, at the start of the Modify Attack Dice step of the attack sequence, before any other effects, the defending unit must flip active shield tokens, if able, for each hit 
or critical 
result in the attack roll, up to X.