Fiendsmith's Agnumday (Super Rare) [ROTA-EN045-SuR]

2+ monsters, including a LIGHT Fiend monster
Once per turn (Quick Effect): You can target 1 LIGHT non-Link Fiend monster in your GY; Special Summon it, and if you do, equip this card you control to that monster as an Equip Spell with the following effects.
• The equipped monster gains ATK equal to the total Link Rating of Link Monsters equipped to it x 600.
• If the equipped monster attacks a Defense Position monster, inflict piercing battle damage to your opponent.