Tapping a multicolored creature using convoke will pay for {1} or one mana of your choice of any of that creature's colors.

If a creature you control has a mana ability with {T} in the cost, activating that ability while casting a spell with convoke will result in the creature being tapped before you pay the spell's costs. You won't be able to tap it again for convoke. Similarly, if you sacrifice a creature to activate a mana ability while casting a spell with convoke, that creature won't be on the battlefield when you pay the spell's costs, so you won't be able to tap it for convoke.

Because convoke isn't an alternative cost, it can be used in conjunction with alternative costs.

You can tap any untapped creature you control to convoke a spell, even one you haven't controlled continuously since the beginning of your most recent turn.

Tapping an untapped creature that's attacking or blocking to convoke a spell won't cause that creature to stop attacking or blocking.

When calculating a spell's total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Convoke applies after the total cost is calculated. Convoke doesn't change a spell's mana cost or mana value.

In some unusual cases—though getting less unusual all the time—a permanent will be comprised of multiple cards, such as a melded permanent or a mutated creature. In those cases, the owner of the permanent puts all those cards second from the top (that is, just under the top card) or on the bottom in any order. Other players get to know which one they chose, but they don't get to know the relative order of the cards.

The owner of the permanent chooses where the card ends up. All players get to know that choice.