Brass's Tunnel-Grinder // Tecutlan, the Searing Rift - Prerelease Promo [PLCI-135s]

When Brass's Tunnel-Grinder enters the battlefield, discard any number of cards, then draw that many cards plus one. At the beginning of your end step, if you descended this turn, put a bore counter on Brass's Tunnel-Grinder. Then if there are three or more bore counters on it, remove those counters and transform it. (You descended if a permanent card was put into your graveyard from anywhere.) // (Transforms from Brass's Tunnel-Grinder.) {T}: Add {R}. Whenever you cast a permanent spell using mana produced by Tecutlan, the Searing Rift, discover X, where X is that spell's mana value.