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 descend if a permanent card was put into your graveyard from anywhere.)

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Tecutlan, the Searing Rift
Legendary Land - Cave
(Transforms from Brass's Tunnel-Grinder.)
: Add .
Whenever you cast a permanent spell using mana produced by Tectulan, the Searing Rift, discover X, where X is that spell's mana value.