Blade Combo

Blade Combos are a mechanic in Xenoblade Chronicles 2 that stack extra damage and effects on enemies when certain sequences of s are used.

Overview
When a is first used on a foe, a level 1 blade combo is applied to that enemy. The element of the combo matches that of the Blade that used the Special. If another Special is then used that fills the requirements of the combo continuing, the level 1 combo is replaced with a level 2 combo. This can be continued to create a level 3 combo, at which point the process resets. Each step in the combo applies an additional package of damage based on the damage dealt by the Special.

There are two requirements for a Special to advance a combo: it must be of a correct element, and its level must exceed the level of the current combo. If these requirements are not met, the combo remains unchanged. For example: There is no advantage or disadvantage to using an over-levelled Special; a level 4 Special will still only move a level 1 combo to a level 2 combo, and a level 3 Special can still advance it from there.
 * A level 1 Special will not advance a level 1 combo. The next Special must be level 2 or higher.
 * An ice Special will not advance a water combo. There are no water combo steps for which ice is a valid next step.

Successfully executing a level 3 combo has two effects.
 * It applies an elemental orb to the enemy, which makes them resistant to further attacks of that element, discouraging the repeated use of the same combo. s can be used to destroy these orbs for extra damage.
 * It activates a Seal, which prevents all enemies in the fight from using a certain mechanic based on the last element in the combo. Only the most recent seal can be active at once.

Steps
Additional technical information can be found at the provided links.

In Torna ~ The Golden Country
Blade Combos are significantly simpler in Torna ~ The Golden Country.
 * Every step of a combo applies an elemental orb, not just the level 3 step.
 * A combo progresses even if the elements used do not match. Instead, matching elements provides extra damage. These are called Critical Routes.