Wand of the Worldsoul

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.

Wotc — January 12, 2024

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.

Wotc — January 12, 2024

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

Wotc — January 12, 2024

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

Wotc — January 12, 2024

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.

Wotc — January 12, 2024

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

Wotc — January 12, 2024

If the next spell you cast after Wand of the Worldsoul's ability resolves already has convoke, giving it convoke again doesn't have any real benefit. Tapping a creature you control will still pay for only {1} or one mana of that creature's color.

Wotc — April 14, 2023