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.

Mass Hysteria · Mirrodin 99/306

Mass Hysteria (Mirrodin 99/306), Rare, Enchantment. Market price $3.57, unchanged this week. Illustrated by Adam Rex. Prices are estimates from TCGPlayer and Cardmarket, not guaranteed values.

Weekly price history

Week	Market price
2026-W31	$3.45
2026-W32	$3.36
2026-W33	$3.43
2026-W34	$3.43
2026-W35	$3.43
2026-W36	$3.49
2026-W37	$3.53
2026-W38	$3.57
2026-W39	$3.57

Questions

How much is Mass Hysteria 99/306 worth?

Mass Hysteria from Mirrodin (99/306) has a market estimate of $3.57, unchanged this week. Prices are estimates from TCGPlayer and Cardmarket.

Is Mass Hysteria 99/306 rare?

It is a Rare from Mirrodin, a 306-card set.

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