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Shonen TCG · General
Reviewing
Union Arena
TL;DR: Union Arena tournament guide for 2026. Decks are exactly 50 cards, max 4 per name, usually single-IP. Sanctioned events run best-of-three Swiss rounds into a single-elimination top cut. Submit a decklist at registration, bring sleeves, a playmat, and counters. Check the official ban list before any event. Locals are walk-in friendly; larger events are stricter on registration and lists.
Union Arena competitive play is approachable once you know the structure. Here is what every new tournament player needs:
Deck rules:
Event structure:
GODEEPER: New to Union Arena entirely? The beginner guide covers the core rules and how a turn works before you compete. Union Arena TCG Beginner Guide 2026
Union Arena's deckbuilding is clean and beginner-friendly compared to some TCGs.
The 50-card deck. Your deck is exactly 50 cards, no more, no less. Sleeve-count carefully before an event, since an incorrect count can cause a game loss at sanctioned tournaments.
The 4-copy limit. You may run up to four copies of any card by name. This is the standard playset cap that shapes most TCG deckbuilding. Build around 4-ofs of your key cards for consistency.
Single-IP focus. Union Arena releases as self-contained single-anime sets: Solo Leveling, Bleach, Jujutsu Kaisen, and more. Most formats expect your deck to be built from one IP. This keeps the game thematic and lets Bandai balance each set internally. Always confirm whether your event allows cross-IP decks, as some open formats do.
The energy system. Unlike One Piece TCG's separate DON!! deck or Magic's lands, Union Arena's energy is integrated into the card system. You do not build a separate resource deck. This streamlines deckbuilding and reduces the resource-screw variance that plagues some other games.
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About the author
TCG Deck Analyst
Former card game tournament organiser turned analyst. Covers One Piece TCG meta, deck efficiency, and card valuation. Builds spreadsheets for decks most people just play.
Disclaimer
This article is published for informational and entertainment purposes. It does not constitute professional financial, legal, or technical advice. Game performance, online services, patch schedules, and store listings change. Verify critical details (pricing, system requirements, regional availability) with publishers and storefronts before you buy. Affiliate links, where present, help support our editorial work and are labelled in our affiliate disclosure.
Understanding match structure changes how you prepare and play.
Best-of-three. Most sanctioned events play matches as best-of-three. The first player to win two games wins the match. After game one, the loser usually chooses who goes first in game two, a meaningful advantage in a tempo-driven game.
Swiss rounds. Tournaments run a set number of Swiss rounds where you face opponents with similar records. A single loss does not eliminate you. Swiss rewards consistency across the whole event, not a single hot streak. The number of rounds scales with attendance.
Top cut. After Swiss, the top players by record advance to a single-elimination bracket. Now a loss ends your run. Top cut is where the pressure peaks and where tight, careful play matters most.
Sanctioned Union Arena events run best-of-three Swiss rounds into a single-elimination top cut. Swiss rewards consistency; a single loss does not end your event until top cut.
Showing up prepared prevents avoidable stress and penalties.
Registration:
What to bring:
Pro tip: Bring a copy of the current rules and ban list on your phone. Disputes happen, and being able to reference the official rules resolves them quickly.
Like One Piece TCG, Union Arena manages power through a limited card list rather than constant errata.
How it works: Bandai Namco restricts or bans cards that prove too dominant. A restricted card is limited to fewer copies; a banned card cannot be played. The list updates periodically, usually alongside new set releases.
Why it matters for you: A deck that was legal last month may be illegal this month if a card was banned. Always check the current official list 1-2 weeks before a sanctioned event. Do not assume a netdeck you found online is still legal.
Format variations: Different events may use different formats: standard single-IP, open cross-IP, or set-specific limited (sealed or draft using a single set's product). Confirm the format when you register so you build the right deck.
Union Arena decks are usually single-IP and exactly 50 cards. Always confirm your event's format and check the official ban list before building, since both can change with new sets.
A few habits separate prepared players from stressed ones.
Practice your matchups. Know how your deck plays against the popular decks in your local meta. Limitless-style results and community discussion reveal what you will likely face.
Tighten your decklist. A consistent 50 beats a flashy but inconsistent one. Run full playsets of your key cards and a reliable curve rather than many one-of tech cards.
Know your lines. Practice your opening turns until they are automatic. In best-of-three with a clock, fumbling early plays wastes time you need later.
Manage the clock. Rounds have time limits. Play at a steady pace, make decisions promptly, and do not slow-play. Going to time in a winning position can cost you the match.
New competitors lose games to avoidable errors more often than to skill gaps. Knowing these in advance protects your record.
Incorrect deck count. The most common disqualifying error is a deck that is not exactly 50 cards. Count your deck twice before submitting your list and again before round one. A 49 or 51 card deck can cost you a game or match at sanctioned events.
Decklist errors. Your physical deck must match your submitted list exactly. A card on your list that is not in your deck, or vice versa, is a penalty. Double-check that your written list reflects the actual cards sleeved.
Slow play. Rounds have time limits. Taking too long on decisions can draw a slow-play warning and, in a winning position, push the game to time before you close it out. Make decisions promptly and keep the game moving.
Marked sleeves. Sleeves that are scuffed, bent, or distinguishable from the back can be ruled as marked cards, a serious penalty. Inspect your sleeves before an event and replace any that stand out. Carry spares.
Forgetting triggers. In the heat of a match it is easy to miss a mandatory ability or an energy step. Build the habit of pausing at each phase to confirm you have done everything before passing priority.
GODEEPER: Not sure which IP set to build for your first tournament? The beginner deck tier list ranks the EN starter sets. Union Arena Beginner Deck Tier List
Q: What are the deck construction rules? A: Exactly 50 cards, max 4 per name, usually single-IP. Energy is built into the system, not a separate deck.
Q: What is the match format? A: Most sanctioned events use best-of-three Swiss rounds into a single-elimination top cut.
Q: How do I register? A: Through your LCS or the official Bandai Namco event system. Submit a decklist and arrive before the cutoff.
Q: Can I mix IP sets? A: Depends on the format. Most formats are single-IP; some open formats allow cross-IP. Confirm your event's rules.
Q: What should I bring? A: 50-card sleeved deck, decklist, playmat, counters, pen, deck box, and spare sleeves. Arrive 15-20 minutes early.
Q: Does Union Arena have a ban list? A: Yes. Bandai Namco maintains a limited card list. Check the current official list before any sanctioned event.
Q: How do Swiss rounds work? A: You play set rounds against similar-record opponents; one loss does not eliminate you. Top players advance to top cut.
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