#trinisphere

Trinisphere

Unspectacularly.

Trinisphere doesn’t care who’s paying the mana to cast a spell, just that at least 3 mana is paid for it. When another player Assists in casting a spell, that mana is still being paid to cast the spell and so Trinisphere will be satisfied just as if the spell’s controller paid all the mana themself.

Trinisphere

You’ll still have to pay 2R for Krenko’s Command.

Improvise is a payment mechanic, so you tap the artifacts as part of paying for the spell. Paying for the spell happens after determining its cost, which is after Trinisphere has applied its effect already.

When you cast a spell with Trinisphere on the battlefield, it will look at the spell's cost once any alternate costs, cost increases, and cost reductions have been applied and then increase the total cost to three mana if it's not already three mana or more.

Phyrexian mana falls afoul of Trinisphere because the choice for whether to pay mana or life for each Phyrexian mana symbol in a spell's cost is made before its final cost is determined. This means that if you choose to pay 2 life instead of U to cast your Gitaxian Probe, Trinisphere isn't going to like that and will make you pay 3 in addition to the 2 life. If you had chosen to pay U, then it would increase the total cost to 2U.

Delve, convoke, and improvise get around Trinisphere's shenanigans because they're payment mechanics that aren't applied until after the total cost of the spell has been determined. So when you cast Gurmag Angler, Trinisphere sees that its total cost is seven and leaves it alone, even if you end up paying for it by only spending B and by exiling six cards from your graveyard.

Trinisphere

"This exhibition of Nehra's Threshold Principle must be expropriated and examined for its potential applications in enforcement." —Confiscation directive

Trinisphere

Designed to restrain petty thoughts, but used to repress entire empires.