Raid Boss

Raid Bosses (レイドボス) are powerful Heartless that appear in Kingdom Hearts χ[chi] and Kingdom Hearts Union χ. They attack Daybreak Town at certain intervals are the main source of Lux. Defeating Raid Bosses is essential to completing daily Team Battles (チームバトル) and boosting the weekly Union Ranking (ユニオンランキング).

Kingdom Hearts χ[chi]
The available Raid Boss changes every two or three weeks. It can be challenged once for free, but afterwards, one must spend Battle Points (BP) to continue fighting it. The amount of BP spent determines damage dealt. Depending on how many allies have already attacked the Raid Boss, a greater Chain Bonus (チェインボーナス) is awarded. A Keyblade Bonus (キーブレードボーナス) can be obtained by facing a Raid Boss with the appropriate Keyblade equipped. One can trigger an EX Card Bonus (EXカードボーナス) to increase damage output by 10.

Rarer versions Raid Bosses, called Ω (亜種), also appear. These provide more valuable rewards, and they have a chance of appearing if the initial Raid Boss is defeated quickly enough.

Kingdom Hearts Union χ
Different Raid Bosses appear based on the missions during which they are summoned. As of Update 1.1.1, there are six total, each with an Ω variant, that spawn during the story and other events. To spawn a Raid Boss, one must defeat a certain number of Heartless each time. These powerful foes typically cost 10 AP to attack; he or she who causes a Raid Boss to appear gets to attack first, for free.

When the player is defeated, his or her party is able to attack a summoned Raid Boss. The enemy must then be defeated within 10 or 20 minutes, depending on its rarity. The goal of all Raid Boss battles is to destroy the Heartless's limbs, and then its main body. Each defeated limb gives the player a free turn to attack.

Eliminating a Raid Boss grants one to three rewards. These come in three categories: Victory, MVP/Host, and All Points Defeated. Rewards given are randomly selected from a group of two to four items; this changes based on a Raid Boss's type and level.