Is there negative Might?

Yes, units in Riftbound can have negative Might values.

According to Rule 143.2.b and associated rulings, while a unit's Might can be reduced below 0, it behaves differently for calculations versus game interactions:

• For Calculation: The game maintains the actual current Might value, including negative numbers. This is important because modifiers are applied to the true current value. For example, if a unit has -3 Might and receives a +2 Might buff, its Might becomes -1, not +2 (see FAQ #9535 and #432).
• For Interactions: Whenever the game checks a unit's Might for game effects (such as during combat damage calculation or determining if it is killed by damage), any negative Might value is treated as 0 (Rule 143.2.b).

Important points to remember:

• Survival: A unit does not die simply by reaching 0 or negative Might. A unit only dies if it has non-zero damage marked on it that is equal to or greater than its Might (Rule 142.2.a and 143.2.a).
• Lethal Damage: Because a unit with 0 or negative Might is treated as having 0 Might for interaction purposes, it will die if it receives at least 1 damage.
• Combat: A unit with negative Might contributes 0 damage in the Combat Damage Step (Rule 143.2.b).

In short: the negative value is tracked mathematically for future adjustments, but it acts as 0 for all active gameplay effects.