Circle of Protection: Blue (Retro) [30th Anniversary Edition] Thopter you may change "swampwalk" to

you may change "swampwalk" to "plainswalk

choose one that hasn't been chosen:

marching over the hills to war

Set: 30th Anniversary Edition Type: Artifact Rarity: Uncommon Cost: {3} Basalt Monolith doesn't untap during your untap step

Set: March of the Machine: The Aftermath Type: Enchantment Rarity: Rare Cost: {3}{R}{W} Creatures you control get +1/+0 and have haste

Circle of Protection: Blue (Retro) [30th Anniversary Edition] Thopter you may change "swampwalk" toSet: 30th Anniversary Edition Type: Enchantment Rarity: Common Cost: {1}{W} {1}: The next time a blue source of your choice would deal damage to you this turn, prevent that damage.