I'm having trouble finding an answer to this. If I have a Lotus Bloom in play, can I declare that I'm casting Whir of Invention, tap Lotus Bloom, and then sacrifice it for UUU to Whir for X=1?
My instinct is to say that it doesn't work, but the weird Krark-Clan Ironworks trick in modern where you overpay an activation cost makes me think this might be legal. Please help me understand. Thank you!
Since Whir of Invention's total cost includes a mana payment here (1UUU if X is 1), you can activate mana abilities before you pay for that spell (C.R. 601.2f-h). You can activate any number of mana abilities this way, and as often as you can pay their costs, even if the mana you add this way exceeds the total cost of the spell (C.R. 117.3). (This is also why, for spells with a mana payment in their total cost, you can activate Krark-Clan Ironworks's mana ability as often as you can pay that ability's cost and before you start to pay for that spell [C.R. 117.3, 601.2g-h, 605.1a].) And since Lotus Bloom's last ability is a mana ability, you can activate it for UUU this way (C.R. 605.1a). If you do, however, Lotus Bloom will have left the battlefield by the time you pay Whir of Invention's cost (C.R. 601.2h); thus you need to have 1 more or control another untapped artifact by that time in order to pay for Whir of Invention if X is 1 (C.R. 701.20a, 702.125a, 701.16a, 117.3). If you can't pay for Whir of Invention, then the casting of Whir of Invention is reversed, as described further in C.R. 721.1 (C.R. 601.2).
On top of Lotus Bloom's cost including sacrifice, both Lotus Bloom's activated ability and the Improvise mechanic require tapping the relevant permanents. You can't tap the same permanent twice.
My instinct is to say that it doesn't work, but the weird Krark-Clan Ironworks trick in modern where you overpay an activation cost makes me think this might be legal. Please help me understand. Thank you!
EDIT (Oct. 11; Dec. 6): Edited.
Two Score, Minus Two or: A Stargate Tail
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