How to play

The rules

A plain-English primer on how Union Arena plays — the cards, the field, building a deck, and the flow of a turn. For the definitive text and rulings, see the official manual.

Official Rule Manual (PDF) ↗

The goal

Reduce their life to zero

Union Arena is a two-player game. You each build a deck around a single anime, game or series and battle. You win the moment your opponent has no cards left in their life area — or can't draw at the start of their turn because their deck is empty.

Each player starts with seven cards face-down in their life area. Direct damage flips those cards; run them out and you lose.

The pieces

The four card types

Character

Your attackers and blockers. Played to the front line or energy line, set to resting. Can be moved during your movement phase.

Site

Support that stays on your field. Only played to the energy line — never the front line — and can't be moved.

Event

One-shot effects. Use the ability, then place the card in your sideline. Playable even when your lines are full.

Action Point

Your resource. Rest an active AP card to pay 1 AP for playing cards and abilities. You run exactly three.

Every playable card shows a required energy (a color + amount your energy line must generate) and an AP cost. The required-energy color is also the card's color. Character and site cards can carry triggers that fire when they're flipped from your life area as you take damage.

The board

Your field

Your side of the table has two battle lines plus five supporting zones:

Front Line — up to 4 · attack & block from here

Energy Line — up to 4 · generates energy; sites live here

Life

7 cards

AP Area

3 cards

Deck

50 cards

Sideline

used / lost

Removal

out of play

Front line and energy line together are your field. Only energy-line cards generate energy.
Sideline holds spent events and defeated cards (face-up). Removal is permanent — gone for the game.

Deck building

Building a legal deck

◆ Exactly 50 cards, plus 3 AP cards kept separately.
◆ Every card shares the same source code — the first three letters of the card number (e.g. all HTR).
◆ At most 4 copies of any one card number.
◆ At most 4 cards of each restricted trigger type — Special, Color, and Final counted separately (up to 12 in total).

The builder enforces these for you — a deck is flagged legal only when all four hold.

The flow

A turn, phase by phase

1
Start Phase
- End effects that last “until your next turn.”
- Switch all your resting cards to active.
- Top up your AP area for the current turn.
- Draw a card (Player One skips this on turn 1).
- Optionally pay 1 AP to draw one extra card.
2
Movement Phase
- Move any number of characters from the energy line to the front line — all at once.
- Characters can only go back to the energy line if they have Step.
- Sites never move.
3
Main Phase
- Play characters, sites and events, or perform Raid — pay the required energy and AP.
- Activate Activate : Main abilities on your field.
- Do these in any order, any number of times.
4
Attack Phase
- Attack with one active front-line character at a time; it switches to resting.
- Attacks target the opponent (or a front-line character via Snipe).
- The defender may block with an active character. No cards can be played this phase.
5
End Phase
- Resolve start-of-end-phase effects.
- Switch your resting characters and sites back to active.
- Discard down to eight cards in hand.
- End “until end of turn” effects. Opponent's turn begins.

Fighting

How combat resolves

An attack is declared by resting an active front-line character. The defender may rest an active character to block. Then it resolves by target:

Attacking a character

Compare BP. If the attacker's BP is equal or higher, the defender is sidelined. If it's lower, the attacker loses — but is not sidelined. BP itself never changes from battle.

Attacking the player

Deal 1 damage (2 with damage ❷). Your opponent flips that many life cards and checks each for a trigger. No life left after checking = you win.

Reference

Keyword abilities

Step↗	During your movement phase, this character may move from the front line back to the energy line.
Snipe↗	May attack a character on the opponent's front line directly — and that attack can't be blocked.
Double Attack↗	The first time it attacks each turn, switch it back to active.
Double Block↗	The first time it blocks each turn, switch it back to active.
Impact ❶↗	When this character attacks and wins a battle, deal 1 damage to your opponent.
Impact +1↗	Increase Impact damage by 1 (grants Impact ❶ if the card had none).
damage ❷	When it attacks and deals direct damage, deal 2 instead of 1.
Nullify Impact↗	The character battling this one loses Impact for the duration of the battle.

Reference

Timing & conditions

Abilities fire at set moments and may carry conditions. The common ones:

When Played

Fires as the card enters your field (including via Raid).

When Attacking

Fires when the card attacks.

When Blocking

Fires when the card blocks.

When Sidelined

Fires when the card is sidelined.

During Your Turn

Stays active for your whole turn.

Once Per Turn

The ability can be used only once per turn, per copy.

Reduce their life to zero

Each player starts with seven cards face-down in their life area. Direct damage flips those cards; run them out and you lose.

The four card types

Character

Your attackers and blockers. Played to the front line or energy line, set to resting. Can be moved during your movement phase.

Site

Support that stays on your field. Only played to the energy line — never the front line — and can't be moved.

Event

One-shot effects. Use the ability, then place the card in your sideline. Playable even when your lines are full.

Action Point

Your resource. Rest an active AP card to pay 1 AP for playing cards and abilities. You run exactly three.

Your field

Your side of the table has two battle lines plus five supporting zones:

Front Line — up to 4 · attack & block from here

Energy Line — up to 4 · generates energy; sites live here

Life

7 cards

AP Area

3 cards

Deck

50 cards

Sideline

used / lost

Removal

out of play

Front line and energy line together are your field. Only energy-line cards generate energy.
Sideline holds spent events and defeated cards (face-up). Removal is permanent — gone for the game.

Building a legal deck

◆ Exactly 50 cards, plus 3 AP cards kept separately.
◆ Every card shares the same source code — the first three letters of the card number (e.g. all HTR).
◆ At most 4 copies of any one card number.
◆ At most 4 cards of each restricted trigger type — Special, Color, and Final counted separately (up to 12 in total).

The builder enforces these for you — a deck is flagged legal only when all four hold.

A turn, phase by phase

1
Start Phase
- End effects that last “until your next turn.”
- Switch all your resting cards to active.
- Top up your AP area for the current turn.
- Draw a card (Player One skips this on turn 1).
- Optionally pay 1 AP to draw one extra card.
2
Movement Phase
- Move any number of characters from the energy line to the front line — all at once.
- Characters can only go back to the energy line if they have Step.
- Sites never move.
3
Main Phase
- Play characters, sites and events, or perform Raid — pay the required energy and AP.
- Activate Activate : Main abilities on your field.
- Do these in any order, any number of times.
4
Attack Phase
- Attack with one active front-line character at a time; it switches to resting.
- Attacks target the opponent (or a front-line character via Snipe).
- The defender may block with an active character. No cards can be played this phase.
5
End Phase
- Resolve start-of-end-phase effects.
- Switch your resting characters and sites back to active.
- Discard down to eight cards in hand.
- End “until end of turn” effects. Opponent's turn begins.

How combat resolves

An attack is declared by resting an active front-line character. The defender may rest an active character to block. Then it resolves by target:

Attacking a character

Compare BP. If the attacker's BP is equal or higher, the defender is sidelined. If it's lower, the attacker loses — but is not sidelined. BP itself never changes from battle.

Attacking the player

Deal 1 damage (2 with damage ❷). Your opponent flips that many life cards and checks each for a trigger. No life left after checking = you win.

Keyword abilities

Step↗	During your movement phase, this character may move from the front line back to the energy line.
Snipe↗	May attack a character on the opponent's front line directly — and that attack can't be blocked.
Double Attack↗	The first time it attacks each turn, switch it back to active.
Double Block↗	The first time it blocks each turn, switch it back to active.
Impact ❶↗	When this character attacks and wins a battle, deal 1 damage to your opponent.
Impact +1↗	Increase Impact damage by 1 (grants Impact ❶ if the card had none).
damage ❷	When it attacks and deals direct damage, deal 2 instead of 1.
Nullify Impact↗	The character battling this one loses Impact for the duration of the battle.

Timing & conditions

Abilities fire at set moments and may carry conditions. The common ones:

When Played

Fires as the card enters your field (including via Raid).

When Attacking

Fires when the card attacks.

When Blocking

Fires when the card blocks.

When Sidelined

Fires when the card is sidelined.

During Your Turn

Stays active for your whole turn.

Once Per Turn

The ability can be used only once per turn, per copy.

Reduce their life to zero

The four card types

Character

Site

Event

Action Point

Your field

Building a legal deck

A turn, phase by phase

Start Phase

Movement Phase

Main Phase

Attack Phase

End Phase

How combat resolves

Attacking a character

Attacking the player

Keyword abilities

Timing & conditions

Reduce their life to zero

The four card types

Character

Site

Event

Action Point

Your field

Building a legal deck

A turn, phase by phase

Start Phase

Movement Phase

Main Phase

Attack Phase

End Phase

How combat resolves

Attacking a character

Attacking the player

Keyword abilities

Timing & conditions