AffinityAffinity is a static ability that functions while the spell with affinity is on the stack. “Affinity for [text]” means “This spell costs less to cast for each [text] you control.”
If a spell has multiple instances of affinity, each of them applies. (CR 702.41) for snow lands (This spell costs
less to
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) for each snow land you control.)
When this creature enters, artifacts and creatures target opponent controls don't
untapTo untap a permanent, rotate it back to the upright position from a sideways position. Only tapped permanents can be untapped. (CR 701.26) during that player's next
untapTo untap a permanent, rotate it back to the upright position from a sideways position. Only tapped permanents can be untapped. (CR 701.26) step.
Return three snow lands you control to their owner's hand: Return this creature to its owner's hand.