Three of the Storm decks from #SCGNY had one Empty the Warrens the maindeck, with Caleb Scherer being the only pilot brave enough to leave all his copies in the sideboard
In most cases (see below), if you wait until the combat damage step or end of combat step, it will be after combat damage has been dealt, so the Ninja won't deal combat damage
It is, however, not an easy card to play correctly, as everyone who has watched control master Guillaume Wafo-Tapa before, will know
Cards like Dracule Mihawk and the Love-Love Mellow event cards, while conditional, can offer players that extra counter that can save their lives
Regardless, Im holding any of these that I open at the prerelease
That being said, dealing damage to battles also effectively increases your opponent's life total