When you deploy a relic using an ability, like Deploy Bone Trap, on a square that contains a stealthed unit, like a Head of Osarius, it doesn't place the relic (which makes sense.) The animation still plays, and the ability still goes on cooldown, but the only indicator that something went wrong is some text in the combat log. It doesn't reveal the stealthed unit like placing a relic from the runedock does.
