Can Gust target a 4 Might unit that has been damaged by Hextech Ray, or does the unit's Might stat need to be reduced below 4?

Question

Accepted Answer

Damage marked on a unit does not change its Might. Gust checks the unit's current Might value, so a 4 Might unit that has been damaged by Hextech Ray is still 4 Might and is not a legal target for Gust unless some other effect actually changed its Might to 3 or less.

No. Gust cannot target a 4 Might unit merely because it has taken damage from Hextech Ray. Damage is marked separately from Might and does not reduce the unit's Might; Gust requires the unit's current Might to be 3 or less to be chosen.

You cast Hextech Ray; it deals 3 damage to the target unit and that damage is marked on the unit as described by [143.3.a]. Gust's targeting restriction is "a unit at a battlefield with 3 :rb_might: or less" — this reads as a check of the unit's current Might value when deciding a legal target, per [710]. Marked damage does not alter a unit's Might; it is a separate tracked quantity and only kills the unit if marked damage >= its Might, per [143.2.a] and [143.3.a]. Therefore a unit with base Might 4 that has taken 3 damage still has a current Might of 4 and is not a legal target for Gust. If the marked damage had been >= its Might, the unit would be Killed and no longer on the board; at that point it would not satisfy "at a battlefield" for Gust and would be in a non-board zone, per [359.3.e.12]. Only if some separate effect actually changes the unit's current Might to 3 or less (for example, a debuff that reduces Might) would Gust be able to target it.

If another effect (not the damage) reduces the unit's Might to 3 or less before playing Gust, Gust can target it because Gust checks current Might [710]. If the unit takes enough damage such that marked damage >= its Might, it will be Killed and moved off the board; it will then no longer be "at a battlefield" and thus cannot be targeted by Gust [143.2.a] [359.3.e.12]. If an effect sets the unit's Might to a negative value, rule [143.2.b] treats that Might as 0 when referenced, which could make it targetable by Gust (since 0 ≤ 3).

The confusion is between damage marked on a unit and the unit's Might value. Hextech Ray deals 3 damage, which is recorded as marked damage on the unit; damage is tracked separately from Might [143.3.a]. A unit is only Killed if its marked damage equals or exceeds its Might [143.2.a]. Nothing in Hextech Ray reduces the unit's Might number. Gust specifically requires a unit "at a battlefield with 3 :rb_might: or less" — that is a check of the unit's current Might stat, evaluated when choosing/targeting, per [710]. Therefore, a base-4 Might unit that has taken 3 damage still has a current Might of 4 and is not a legal target for Gust. If the unit were instead reduced to 3 or less by some effect that changes Might, Gust could target it. If the unit took damage equal to or greater than its Might it would be Killed and moved off the board, and thus would no longer be "at a battlefield" for Gust to target [143.2.a] [359.3.e.12].