new graves unit with 4 might, 5 energy cost and 1 body power. when it attacks or defends it deals damage equal to its might to all enemy units here. and it does not deals combat damage. how to counter this? seems too op

Radiance rules aren't published yet. This uses the printed card and current rules only, and it isn't a ruling on the new mechanics.

I can't verify that card — there is no Graves unit in my card database, and no FAQ or errata entry for it — so I can't confirm the cost, Might, or the exact wording, and I won't rule on numbers I can't read.

If the text is as you describe, the relevant rules are these: the attack/defend damage is a triggered ability dealing non-combat damage, so it's placed on the Chain and opponents can respond before it resolves, and things like "here," "enemy," and the unit's current Might are checked when that instruction executes (Rule 359.3.f.4). So the available counterplay is Chain interaction — prevent the damage, reduce its Might before the trigger resolves (the damage equals its current Might, Rule 710), or remove/recall the unit so the board it's checking changes.

One consequence worth knowing: because the damage isn't combat damage, Stun doesn't stop it (stun only prevents a unit dealing combat damage), and the unit contributes nothing to the Combat Damage Step's Might sum, so Tank/Shield ordering and combat-damage modifiers won't interact with it normally. Whether it's actually overpowered is a balance question, not a rules one — I don't have the card to evaluate.

This is my interpretation based on Rules 710, 465.2, and 359.3.f.4. No official FAQ exists for this specific interaction.