Can I build a deck together with friends on TCGSwap?

Yes. Every deck on TCGSwap has a Collaboration Space. You can invite up to 5 friends; they can suggest card changes, discuss ideas, and playtest proposals. You review and apply suggestions before anything changes in your deck.

How does deck collaboration work?

It works like a pull request for your deck. Collaborators open the deck editor, make their proposed changes, and submit a suggestion with a note. You get notified, open the comparison view to see exactly what they changed, and choose to apply all, cherry-pick individual cards, or decline. Nothing changes in your deck until you approve it.

Can collaborators chat and discuss the deck?

Yes. The Collaboration Space has a shared group discussion thread for the whole deck, plus a per-suggestion Q&A thread for each proposal. You can @mention teammates and link specific cards inline.

Is collaborative deck building free?

Yes, collaboration is free for all TCGSwap users during beta. You can invite up to 5 collaborators per deck.

Does TCGSwap work for MTG, Pokémon, Yu-Gi-Oh and One Piece collaboration?

Yes. The Collaboration Space supports all four games — Magic: The Gathering, Pokémon TCG, Yu-Gi-Oh and One Piece. Format validation and card prices are included for each game.

Gem-Knight Hollowcore · Battles of Legend: Monster Mayhem 88225269/177

Gem-Knight Hollowcore (Battles of Legend: Monster Mayhem 88225269/177), Secret Rare. Market price $0.31, up 10.7% this week. Prices are estimates from TCGPlayer and Cardmarket, not guaranteed values.

You can send 1 "Gem-Knight" Normal Monster or 1 "Gem-Knight Fusion" from your Deck to the GY; Special Summon this card from your hand in Defense Position. When your opponent activates a card or effect, while you control a "Gem-Knight" Fusion Monster (Quick Effect): You can banish 3 "Gem-Knight" cards from your GY, including this card; negate that effect, then all "Gem-Knight" monsters you currently control gain 1000 ATK. You can only use each effect of "Gem-Knight Hollowcore" once per turn.

Weekly price history

Week	Market price
2026-W31	$0.31
2026-W32	$0.33
2026-W33	$0.30
2026-W34	$0.28
2026-W35	$0.28
2026-W36	$0.28
2026-W37	$0.31

Questions

How much is Gem-Knight Hollowcore 88225269/177 worth?

Gem-Knight Hollowcore from Battles of Legend: Monster Mayhem (88225269/177) has a market estimate of $0.31, up 10.7% this week. Prices are estimates from TCGPlayer and Cardmarket.

Is Gem-Knight Hollowcore 88225269/177 rare?

It is a Secret Rare from Battles of Legend: Monster Mayhem, a 177-card set.

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