Silvera, Wolf Tamer of the White Forest

Level 6 LIGHT/Spellcaster Synchro Tuner Effect
1900 ATK / 2400 DEF

1 Tuner + 1+ non-Tuner monsters
If this card is Special Summoned: You can change all face-up monsters your opponent controls to face-down Defense Position. Illusion and Spellcaster Synchro Monsters you control gain 500 ATK, also if they attack a Defense Position monster, inflict double piercing battle damage to your opponent.

Rulings – Yugipedia

Printings:

The Infinite Forbidden: INFO-EN038 (Quarter Century Secret Rare) - 2024-07-18
The Infinite Forbidden: INFO-EN038 (Ultra Rare) - 2024-07-18
2025 Mega-Pack Tin: MP25-EN086 (Prismatic Secret Rare) - 2025-09-04

Prices:

Cardmarket: 0.74 €
TCGplayer: $ 0.73