In the vast majority of games, the life that your opponent gains from you nuking their creatures with Swords to Plowshares will not amount to much, unless theyre playing a black deck with life-to-resource cards (watch out for Toxic Deluge or worse, Yawgmoths Bargain !) Swords to Plowshares isnt a particularly expensive card, and its very easy to find
View the complete card list with images, prices, and rarity information on the XY - Evolutions binder layout page on Cardrake
Once per turn, during your Standby Phase: Place 1 Signal Counter on this card
Somehow the most popular Boros commander ever, by a wide margin, is dirt cheap
They did the same with Antique Old Amber and Aerodactyl ex, so it's not just Unfezant