Koskun Falls [Homelands] World Championship Promos Set: Unlimited Edition Type: Artifact

Set: Unlimited Edition Type: Artifact Rarity: Rare Cost: {3} You may spend white mana as though it were red mana

This explains why the goblins remain unaffected

You may exile two blue cards from your hand rather than pay this spell's mana cost

As long as you have 0 or less life

Set: Kaladesh Inventions Type: Artifact — Equipment Rarity: Mythic Cost: {3} Equipped creature gets +2/+2 and has protection from red and from blue

Koskun Falls [Homelands] World Championship Promos Set: Unlimited Edition Type: ArtifactSet: Homelands Type: World Enchantment Rarity: Rare Cost: {2}{B}{B} At the beginning of your upkeep, sacrifice Koskun Falls unless you tap an untapped creature you control. Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.