Raffine, Scheming Seer
Legendary Creature — Sphinx Demon
Flying, ward 
Whenever you attack, target attacking creature connives X, where X is the number of attacking creatures. (Draw X cards, then discard X cards. Put a +1/+1 counter on that creature for each nonland card discarded this way.)
Johannes Voss
Rulings
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.
(wotc • 2024-04-12)
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.
(wotc • 2024-04-12)
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.
(wotc • 2022-04-29)
Rulings
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.
(wotc • 2024-04-12)
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.
(wotc • 2024-04-12)
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.
(wotc • 2022-04-29)