Damon Dash's Rap Ex -- Cops Called In Nasty Custody War

Rap mogul Damon Dash's ex-wife had the cops waiting for him at his house because her kid has been AWOL from school ... and she claims there's a more serious issue ... he's an abusive stoner with a history of domestic violence.

According to court docs ... Dash's ex, fashion designer Rachel Roy, wants his visitation rights taken away because she says he's an unfit father to daughters Ava and Tallulah.

Damon says she's using the kids as pawns and this is some kind of power play on his ex's part, but he's not specific as to what he believes she wants from him. He posted video showing the LAPD waiting for him last week, saying this is all just harassment on her part.

Roy makes other claims as well in her docs, saying Dash kidnapped their daughter from a nail salon. He says she's ridiculous because he's her dad and it's not kidnapping.