One of your opponent's units in the Ground or Character arena loses Stealth until end of turn. Play only during your build step.
Keywords
Resilience
Resilience X: A cumulative, static ability that means, "As long as this unit has at least X damage counters on it, it gets +X power."
Stealth
Stealth: An isolated, static ability that means, "This unit can't be attacked unless it's tapped or has damage counters on it." An untapped and undamaged unit with Stealth can still be affected by alternative types of damage. (Such as Overkill.) As long as the unit has any number of damage counters on it, it can't use Stealth.