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.

Eidos the Underworld Monarch · Duelist's Advance 31596518/48

Eidos the Underworld Monarch (Duelist's Advance 31596518/48), Starlight Rare. Market price $2.77, down 3.8% this week. Prices are estimates from TCGPlayer and Cardmarket, not guaranteed values.

If this card is Normal or Special Summoned: You can add 1 "Monarch" Spell/Trap or 1 monster with 2800 ATK/1000 DEF from your Deck or GY to your hand. You can declare 1 Attribute; make 1 face-up monster on the field become that Attribute. If you Tribute Summon a monster with 2400 or more ATK and 1000 DEF, while this card is in your GY: You can add this card to your hand or Special Summon it. You can only use each effect of "Eidos the Underworld Monarch" once per turn.

Weekly price history

Week	Market price
2026-W31	$2.88
2026-W32	$2.77
2026-W33	$2.60
2026-W34	$2.69
2026-W35	$2.69
2026-W36	$2.88
2026-W37	$2.77

Questions

How much is Eidos the Underworld Monarch 31596518/48 worth?

Eidos the Underworld Monarch from Duelist's Advance (31596518/48) has a market estimate of $2.77, down 3.8% this week. Prices are estimates from TCGPlayer and Cardmarket.

Is Eidos the Underworld Monarch 31596518/48 rare?

It is a Starlight Rare from Duelist's Advance, a 48-card set.

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