2022-04-29 : Because convoke isn't an alternative cost, it can be used in conjunction with alternative costs.

2022-04-29 : Convoke doesn't change a spell's mana cost or mana value.

2022-04-29 : 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.

2022-04-29 : If a resolving spell or ability instructs a specific creature to connive but that creature has left the battlefield, the creature still connives. If you discard a nonland card this way, you won't put a +1/+1 counter on anything. Abilities that trigger "when [that creature] connives" will trigger.

2022-04-29 : If no card is discarded, most likely because that player's hand is empty and an effect says they can't draw cards, the conniving creature does not receive a +1/+1 counter.

2022-04-29 : Once an ability that causes a creature to connive begins to resolve, no player may take any other actions until it's done. Notably, opponents can't try to remove the conniving creature after you discard a nonland card but before it receives a counter.

2022-04-29 : Tapping a multicolored creature using convoke will pay for {1} or one mana of your choice of any of that creature's colors.

2022-04-29 : 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.

2022-04-29 : When multiple creatures are instructed to connive simultaneously, they connive one at a time in the order of their controller's choice.

2022-04-29 : You can tap an untapped creature you haven't controlled continuously since the beginning of your most recent turn to convoke a spell.

2022-04-29 : You can't tap more creatures to convoke Lethal Scheme than it takes to pay for its total cost. This means that normally no more than four creatures can convoke it.