Xenosaga Episode I Reference

Battle Mechanics

Most difficult fights become much more manageable once you treat AP, Boost, and the as resources you can schedule instead of decorations around the battle screen.

Read the battle screen

Display	What to watch
AP	Each action has a cost. A character normally gains 4 AP at the start of a turn and can hold up to 6.
Group Turn Window	Shows which character or enemy acts next. Use it before committing to a long attack or claiming a Boost turn.
Boost Gauge	Each full level can insert an eligible character into the turn order. Physical attacks fill it; Ether abilities do not.
Event Slot	Applies its current effect to whoever is acting, including enemies. The fixed order is blank, Critical Rate Up, Boost Gauge Up, then Points Up.
Target information	Search Eyes or Analyze exposes HP and enemy details so you can time a finishing blow instead of guessing.

AP: save two now, spend six next turn

A character normally starts a turn with 4 AP. Unspent AP carries forward, but the total cannot exceed 6. That makes one of the most useful rhythms:

Spend 2 AP on one normal attack, then press X to end the attack string.
Carry the remaining 2 AP into the next turn.
Add the normal 4 AP at the start of that turn for the 6 AP needed by slower attacks and special commands.

Action	AP	Practical use
Square or Triangle normal attack	2 per attack	Use one attack and stop when you want to carry 2 AP.
Guard	2	Reduce incoming damage and prepare 6 AP for the next turn.
Move	2	Change rows or move behind another character.
Item	3	Use one ordinary item.
Ether	4	Cast one equipped Ether ability.
Board or leave an A.G.W.S.	4	Change between on-foot and A.G.W.S. combat.
KOS-MOS or Ziggy subweapon	6	Press Circle before any normal attack.
	6	Spend two copies of an item to affect the whole party.
	6	Fire matching compatible left- and right-hand A.G.W.S. weapons together.

Normal attacks and Tech Attacks

Square and Triangle attacks cost 2 AP each. Circle selects a Tech Attack after the required normal attacks have built its command string.

Tech speed	Input pattern	Total AP
LW	Square or Triangle, Square or Triangle, Circle	6
HI	Square or Triangle, Circle	4

Upgrading a useful Tech Attack from LW to HI usually helps more than buying its first few raw power levels because you can use it from an ordinary 4 AP turn. Wait controls how long the character must recover before that Tech Attack becomes available again; lowering it toward A0 makes repeated use easier.

changes the 6 AP string. With the Skill equipped, Square, Circle, Circle and Triangle, Circle, Circle both work, so the first normal attack does not have to use a particular button.

KOS-MOS and Ziggy also have 6 AP subweapon attacks assigned to Circle. Select the subweapon before pressing Square or Triangle; once a normal attack starts, the subweapon is no longer available in that string.

See Tech Attacks for the complete character list.

Event Slot

The advances in the same four-step order throughout the battle. Its starting position is random unless a field trap changes the opening state.

Slot	What it does	Best response
Blank	No special effect.	Heal, set up, or advance the cycle.
Critical Rate Up	Raises the chance of critical physical attacks for the current actor.	Use a strong attack when it belongs to you; avoid handing it to a dangerous enemy.
Boost Gauge Up	Increases Boost Gauge gain from attacks during the current turn.	Use a multi-hit attack. Ether abilities do not build the gauge.
Points Up	Gives a random 2x, 4x, or 10x multiplier to the T.Pts, E.Pts, and S.Pts from each enemy defeated on that turn.	Use Boost and target HP information to land as many finishing blows here as practical.

The multiplier belongs to each enemy defeated on that turn, not merely to the battle’s final enemy. If one attack defeats several enemies on the slot, each of those enemies contributes multiplied points.

Boost and turn manipulation

Boost lets you insert an eligible party member immediately after the current action:

Check the and the next .
Hold R1 or R2 to display the Boost controls.
Press the face button corresponding to the character’s position in the party display.
Finish the current action. The selected character takes the next turn.

A character cannot claim a Boost turn while already acting or already shown in the , and only one character can reserve the next turn. can override an ordinary Boost and insert the responding enemy or character first.

Use Boost to heal before an enemy acts, keep a dangerous away from a boss, or move a prepared attacker onto . is especially useful because it grants a Boost level to any party member instead of waiting for that character to fill the gauge.

Guard, Move, and formation

Command	What it changes
Guard	Costs 2 AP, improves the character’s chance to defend against incoming damage, and leaves 2 AP to carry into the next turn. It is the simplest setup for a 6 AP action.
Move	Costs 2 AP and changes formation. A character in the rear row takes less damage but can use only Items and Ether until moved forward.
Move behind an ally	Prevents enemies from pushing that character backward. This is useful when you need a healer or support character to stay in a predictable row.

Both commands consume the current turn, so they also advance the . Guard when you want 6 AP next turn; Move when the formation change itself matters.

Who receives battle points

, , and from defeated enemies are divided among the surviving members of the active battle party. If a temporary companion falls, the remaining survivor receives a larger share. Do not sacrifice a useful party member casually, but this explains why the same fight can produce different individual totals.

A.G.W.S. battle differences

Boarding or leaving an A.G.W.S. costs 4 AP. While boarded, a character uses the unit’s commands and cannot use ordinary Items or Ether. Guard for one turn to reach 6 AP, then use with matching compatible weapons when you need one large attack instead of several weaker hits.

The dedicated A.G.W.S. reference covers units, frames, generators, weapons, ammunition, accessories, and upgrades.