Assault Counter, or AC for short, is a battle feature characteristic to the Linear Motion Battle System versions present in Tales of Xillia and Tales of Xillia 2. It is based on the concept of Chain Capacity, but instead of each arte having a different AC cost, every arte costs 1 AC to execute; therefore, Assault Counter governs the length of the arte chain each character can execute. AC is also expended when performing normal attacks and quick-stepping.
Tales of Xillia
In Tales of Xillia, each character begins with 3 AC, which can be further increased by equipping "Assault"-line and/or "Linked Action" skills. AC cost for quick-stepping can be nullified with the "Mirage Step" skill, and equipping the "Momentary Gain" skill will earn up to 3 AC when evading enemy's ground physical attacks.
Tales of Xillia 2
In Tales of Xillia 2, AC is tied to weapons, and each weapon has a fixed AC. "Linked Action" and "Momentary Gain" skills return with their effects unchanged. Certain artes gain a chance to nullify their AC cost as they are leveled up with extractors via Allium Orbs. At 4,000 uses and above, there is a 25% chance to nullify the AC cost of an arte if it is used consecutively. This effect can be improved to a 50% chance with 9,999 uses. While Ludger Will Kresnik is in the chromatus form, the limits of Assault Counter are nullified.