Deck building

A legal Union Arena deck is 50 cards, plus a separate 3-card AP (Action Point) pool that isn't part of your main 50. Before the game starts, you also set aside 7 cards from your deck face-down as your Life Area - your life total for the match.

Every card in your deck has to share the same "source" IP (the first letters of its card number), you can only run up to 4 copies of any single card, and the three "restricted" Trigger types - Special, Color, and Final - are capped at 4 copies each, with a combined maximum of 12 across all three. Get and Draw triggers have no such cap.

Turn structure

Each player's turn moves through five phases, always in the same order:

1. Start Phase

   Rested cards in your Front Line and Energy Line become active again, your AP Area refills, and you draw a card (the very first player skips this draw on turn one).

2. Movement Phase

   Move Characters from your Energy Line onto your Front Line, or the reverse, to set up who can attack or generate energy this turn.

3. Main Phase

   Play Characters, Events, and Sites, spend AP and energy, and activate abilities in whatever order makes sense for your plan - you can do this multiple times.

4. Attack Phase

   Your active Front Line Characters attack one at a time. Your opponent can block each attack before you move to the next.

5. End Phase

   Any end-of-turn effects resolve, your cards reset to active, and you discard down to the hand size limit before play passes to your opponent.

Combat and stats

Characters are deployed by spending energy generated from your Energy Line, and each one carries a BP (Battle Point) value - the stat that decides fights. When a Character attacks and your opponent blocks with one of theirs, the two BP values are compared: the lower BP Character is sent to the Sideline. If BP is equal or your Character's is higher, your attacker wins the exchange and survives.

If an attack goes unblocked, it hits your opponent directly - flipping a card from their Life Area into their hand and checking it for a Trigger effect. Some card effects deal extra damage, flipping more than one Life card at once.

Trigger types

Every Life card can carry a Trigger effect that fires the moment it's taken from damage. There are six types - see the full card glossary for more terminology like this.

Get

The baseline trigger type - the effect is different on every card, so you read exactly what the revealed Life card says.

Draw

Draw an extra card on top of the Life card you just took, giving you a small burst of card advantage when you take damage.

Color

A steady effect tied to your deck's color identity, giving reliable value that helps stabilize your board after taking a hit.

Special

A powerful, card-specific effect - these are usually the strongest and most build-around trigger effects in the game.

Active

Sets a Character on your field back to active and can grant a temporary bonus, often opening up a surprise block or an extra attack.

Final

Built for comebacks - Final triggers are printed to be especially strong when you're already low on Life, rewarding decks that can play from behind.

Winning the game

You win by reducing your opponent's Life Area to zero cards, or if your opponent is unable to draw a card at the start of their turn because their deck is empty. Every point of Life damage is also a Trigger check, so even a "losing" attack can hand your opponent exactly the card they needed - which is why sequencing your attacks carefully matters as much as raw BP.