Summoning Trap
Instant — Trap
If a creature spell you cast this turn was countered by a spell or ability an opponent controlled, you may pay 
rather than pay this spell's mana cost.
Look at the top seven cards of your library. You may put a creature card from among them onto the battlefield. Put the rest on the bottom of your library in any order.
Illustrated by
Modern Masters 2017#139RareEnglishLegality
Rulings
You may ignore a Trap’s alternative cost condition and simply cast it for its normal mana cost. This is true even if its alternative cost condition has been met.
Casting a Trap by paying its alternative cost doesn’t change its mana cost or converted mana cost. The only difference is the cost you actually pay.
Effects that increase or reduce the cost to cast a Trap will apply to whichever cost you chose to pay.
If there are seven or fewer cards in your library, you’ll look at all of them.