Steelswarm Gatekeeper

Level 4 DARK/Fiend Effect
1500 ATK / 1900 DEF

If a "Steelswarm" monster is Tribute Summoned face-up while this card is face-up on the field, you can Normal Summon or Set 1 monster in addition to your Normal Summon or Set that turn.

Rulings – Yugipedia

Printings:

Duel Terminal 5b: DT05-EN078 (Duel Terminal Normal Parallel Rare) - 2011-09-29
Hidden Arsenal 5: Steelswarm Invasion: HA05-EN045 (Super Rare) - 2011-12-01

Prices:

Cardmarket: 0.21 €
TCGplayer: $ 0.17