Mask of the Schemer

Whenever equipped creature deals combat damage to a player, it connives X, where X is the amount of damage it dealt to that player. (Draw X cards, then discard X cards. Put a +1/+1 counter on that creature for each nonland card discarded this way.)
Equip {2}

New Capenna Commander

Whenever equipped creature deals combat damage to a player, it connives X, where X is the amount of damage it dealt to that player.
Equip {2}

New Capenna Commander Promos

Connive X is a variant of connive. If a creature connives X, its controller will draw X cards, discard X cards, then then put a number of +1/+1 counters on the conniving permanent equal to the number of nonland cards discarded this way.

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.

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.

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.