What occurs when a unit is affected by the "Stun" effect?

When a unit is affected by the "Stun" effect, it is unable to engage in combat this turn, which includes the inability to deal damage. Stun temporarily incapacitates the unit, thus preventing it from taking actions that would normally happen during that phase. This makes option B the correct choice, as it directly aligns with the mechanics of how "Stun" operates within the context of the game.

The other choices do not accurately depict the effects of the Stun status. For instance, while the unit loses some functionality due to being stunned, it does not completely lose all abilities, nor does it gain additional turns or extra attacks, which more closely defines other status effects or bonuses rather than the Stun effect. Understanding the nuances of Stun and how it impacts gameplay is crucial for strategic play in Riftbound.