Tempest Technique is a rare Enchantment — Aura card from Tarkir: Dragonstorm Commander (TDC), collector number 56. Current market price: $2.17, TCGplayer market prices via Scryfall.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies. Copies become tokens.) Enchant creature you control Enchanted creature gets +1/+1 for each enchantment you control.