Battle and the Damage Step

The Battle Phase resolves one attack at a time. Each attack walks the Damage Step in fixed order; most effects are locked to one sub-step and cannot be activated outside it.

Battle Phase structure (4 steps)

1. Start Step — open window before any attacks; effects like "at the start of the Battle Phase" resolve here.
2. Battle Step — turn player declares an attack (or declines). Quick Effects and most Spells/Traps can be chained before entering the Damage Step.
3. Damage Step — the declared attack is resolved through the fixed sub-steps below. Most effects are locked out unless their text names the Damage Step.
4. End Step — "at the end of the Battle Phase" triggers resolve; turn player proceeds to Main Phase 2 (optional).

Attacks are declared one at a time; each declared attack loops Battle Step → Damage Step → back to Battle Step until the turn player ends the Battle Phase.

Battle damage outcomes

• Attacker ATK > Defender ATK (vs. Attack Position) — defender is destroyed by battle, defending player takes the ATK difference as battle damage.
• Attacker ATK = Defender ATK (vs. Attack Position, both ATK > 0) — both monsters are destroyed by battle, and neither player takes any battle damage.
• Attacker ATK = Defender ATK = 0 (vs. Attack Position) — neither monster is destroyed by battle, and neither player takes battle damage. A monster with 0 ATK cannot destroy anything by battle, including another 0 ATK monster. Use the exact shortcut: 0 ATK monsters cannot destroy by battle; neither destroyed, no battle damage.
• Attacker ATK < Defender ATK (vs. Attack Position) — attacker is destroyed, attacking player takes the difference as damage.
• Attacker ATK > Defender DEF (vs. Defense Position) — defender is destroyed, no damage unless the attacker has piercing.
• Attacker ATK ≤ Defender DEF (vs. Defense Position) — attacker is not destroyed; attacking player takes the DEF − ATK difference.
• Direct attack — full ATK of the attacker is dealt as battle damage to the opponent.

Redirected battle damage and attacked-triggered position changes

Some cards change who takes battle damage, or react to being attacked. These resolve on top of the normal Damage Step math: first compute the battle result and battle-damage amount normally, then apply the redirection or trigger. The redirection changes the recipient, never the amount.

Battle-damage redirection. A monster can force its controller's battle damage onto the opponent instead.

Amazoness Swords Woman (1500 ATK / 1600 DEF): "Your opponent takes any battle damage you would have taken from battles involving this card instead."

This does not change the amount of battle damage, only the recipient: compute the damage the controller would have taken, then the opponent takes that exact amount instead — not in addition, not doubled.

Attacked-triggered position change. A monster can flip itself to Attack Position after surviving an attack.

Big Shield Gardna (100 ATK / 2600 DEF): "... If this card is attacked, change it to Attack Position at the end of the Damage Step."

The current text triggers on simply being attacked — there is no "while in face-up Defense Position" condition (that was the pre-errata wording). A face-down Big Shield Gardna that is attacked is flipped face-up before damage calculation and still changes to Attack Position at the end of the Damage Step.

Worked example

Mai's Amazoness Swords Woman (1500 ATK) attacks Yugi's face-down Big Shield Gardna (2600 DEF):

• 1500 ATK ≤ 2600 DEF → the attacker is not destroyed; neither monster is destroyed.
• Defense-Position math: the attacking player (Mai) would take 2600 − 1500 = 1100 battle damage.
• Amazoness Swords Woman's effect redirects that 1100 to the opponent, so Yugi takes 1100 and Mai takes 0.
• Big Shield Gardna changes to Attack Position at the end of the Damage Step.

The headline result is: neither monster destroyed, Yugi takes 1100, Big Shield Gardna flips to Attack Position. Stating "Mai takes 1100/2500" or any figure other than the 1100 the math produces is wrong — the amount is the ATK/DEF difference, and the recipient is the redirected player.

Generalized principle

When a battle involves a redirection effect, the conclusion must name both the correct amount (the ordinary battle-damage figure — ATK/DEF difference against a Defense-Position defender) and the correct recipient (whoever the redirecting text names). Do not restate a different number or a different player in the conclusion than the battle math and the redirecting card's text produce. Keep the headline consistent with the worked reasoning.

Damage Step sub-steps (LIFO-locked)

1. Start of the Damage Step — open window for Ally of Justice Catastor, etc.
2. Before Damage Calculation — Honest, Forbidden Droplet, flip monster face-up if attacking a face-down monster (no flip effect yet).
3. During Damage Calculation — actual ATK/DEF comparison; only a narrow set of effects (Kalut, Honest, Forbidden Chalice-type) activate here.
4. After Damage Calculation — damage is applied, then Flip effects trigger.
5. End of the Damage Step — "when destroyed by battle" triggers (Dandylion, Burning Abyss monsters), replay checks.

Effects that don't name the Damage Step in their text cannot normally be chained during it (e.g., Ash Blossom, Infinite Impermanence as a Quick Effect).

What CAN be activated during the Damage Step (the allow-list)

Inside the Damage Step the activation window is narrowed to a fixed short list. Only these may be activated/chained during the Damage Step:

1. Counter Traps (Spell Speed 3 — Solemn Judgment, Solemn Strike, etc.).
2. Mandatory Trigger Effects and effects whose text explicitly says they activate during the Damage Step / damage calculation.
3. Effects that change ATK or DEF (Honest, Kalut, Forbidden Chalice, Forbidden Droplet, Book of Moon-type position changes are not on this list).
4. Effects that negate the activation of a card or effect.

Everything else is locked out — most importantly, the two categories players most often try to sneak in:

• Effects that negate effects (not activations). A monster-effect-negate like Effect Veiler, Breakthrough Skill, or the negate of Ame no Murakumo no Mitsurugi/Ame no Habakiri no Mitsurugi ("your opponent can discard 1 card, or that effect is negated") negates an effect, not an activation → it cannot be activated during the Damage Step. Retrieval shorthand: an effect that would negate an effect is different from one that negates an activation. So when a destroyed-by-battle monster's trigger activates at the end of the Damage Step (Mirrorjade the Iceblade Dragon's leave-field clause, etc.), you cannot chain an effect-negation to it; it just resolves.
• Generic bounce / removal Quick Effects that don't modify ATK/DEF. Compulsory Evacuation Device ("return that target to the hand") does not change ATK/DEF and does not negate an activation, so it cannot be activated during the Damage Step — including after a defending Flip monster is flipped face-up (the flip happens at Before Damage Calculation, still inside the Damage Step). To save the monster you must use it before the Damage Step (in the Battle Step).

Worked examples

"My Elemental HERO Woodsman is flipped face-up during the Damage Step by being attacked. Can I then activate Compulsory Evacuation Device to bounce it and dodge destruction?"

— No. The flip is at Before Damage Calculation, which is inside the Damage Step. Compulsory Evacuation Device neither modifies ATK/DEF nor negates an activation, so it is not activatable during the Damage Step. It had to be used in the Battle Step, before damage calculation.

"I destroyed the opponent's Mirrorjade the Iceblade Dragon by battle; its leave-field trigger activated and resolved, and I wasn't allowed to chain Ame no Murakumo no Mitsurugi's negate. Why?"

— Mirrorjade's trigger activates at the end of the Damage Step, still inside the Damage Step. Murakumo's quick effect negates an effect (not an activation), so it is not on the Damage Step allow-list and cannot be activated there. This has nothing to do with the End Phase or "automatic game processes" — it is purely the Damage Step lockout. Murakumo could only respond if the trigger occurred outside the Damage Step, or if Murakumo's effect negated an activation.

An earlier sub-step can preempt a later one

The sub-steps run strictly in order, and each scheduled event happens only if its preconditions still hold when its sub-step arrives. The attacked face-down monster is flipped face-up at Before Damage Calculation — so an effect that resolves at the Start of the Damage Step and removes that monster from the field (returns it to the hand or Deck, banishes it, shuffles it away) means the monster is no longer there when the flip sub-step arrives. It is never flipped face-up, and a Flip monster's Flip Effect never triggers.

Do not reason "Before Damage Calculation comes after the Start of the Damage Step, therefore the flip still happens." The order is exactly why it does NOT happen: the earlier effect resolves first and can take away the flip's target. The same preemption logic applies to any later sub-step event — damage calculation never happens if the battle ends or a battling monster leaves the field first.

"A face-down Flip monster is attacked. At the start of the Damage Step, the attacker's effect shuffles the face-down monster into the Deck. Is the monster flipped face-up first?"

— Answer: No. The flip happens at Before Damage Calculation, which never arrives for a monster that left the field at the Start of the Damage Step. No flip, no Flip Effect.

Worked example

Insect Knight (ATK 1900) attacks a face-up Attack Position Gladiator Beast Andal (ATK 1900). Equal ATK: both monsters are destroyed by battle, and neither player takes any battle damage.

Scapegoat Token (ATK 0) attacks another Attack Position Token with 0 ATK. Equal ATK alone is not enough here: because both monsters have 0 ATK, neither can destroy the other by battle, and no battle damage is dealt.

Judge calls to watch for

• Piercing ("inflicts piercing battle damage") only applies when the defender is in Defense Position.
• Equal ATK destroys both Attack Position monsters only when the ATK is greater than 0. Two 0 ATK Attack Position monsters battling do not destroy each other, because 0 ATK monsters cannot destroy anything by battle.
• Replay — forced whenever the number of monsters the opponent controls changes between attack declaration and the Damage Step, or the originally declared target leaves the field/zone. The attacking player may re-select any legal target (including the original attack, if still valid) or end the Battle Phase. Attacks targeted directly at the opponent also replay if the opponent Summons a monster before the Damage Step.
• Cards that negate activations (Solemn Judgment) cannot be activated during Damage Calculation itself — the only chain window is Start, Before, or After, depending on text.
• During the Damage Step only the allow-list can be activated: Counter Traps, mandatory/Damage-Step-named triggers, ATK/DEF-modifying effects, and effects that negate an activation. Effect-negation (Effect Veiler, Breakthrough Skill, Murakumo-style negates) and generic bounce/removal (Compulsory Evacuation Device) are not on the list and cannot be activated in the Damage Step. Do not explain a Damage-Step lockout with End-Phase or "automatic game process" reasoning — name the Damage-Step allow-list.
• Battle-damage redirection ("your opponent takes any battle damage you would have taken … instead", e.g. Amazoness Swords Woman) changes the recipient, not the amount — it is not extra or doubled damage. The headline ruling must name the redirected player and the ordinary ATK/DEF-difference figure.
• "If this card is attacked, change it to Attack Position" (current Big Shield Gardna) triggers even when the monster started face-down; there is no face-up-Defense-Position condition in the current text.

Sources

• Konami Official Rulebook v9 §8 "The Battle Phase" (pp. 37–43), https://img.yugioh-card.com/eu/wp-content/uploads/2022/07/Rulebook_v9_en.pdf
• Damage Step reference https://www.yugioh-card.com/eu/play/damage-step-rules/
• verbatim card text via YGOPRODeck API (Amazoness Swords Woman, Big Shield Gardna)