Uno reverse

You present the UNO card to a creature in the process of casting a spell to attempt to reverse the effect of the spell. If the creature is casting a spell of 8th level or lower, its spell succeeds but the effect is reversed. If it is casting a spell of 9th level, make an ability check using your spellcasting ability. The DC equals 19. On a success, the creature’s spell gets reversed anyway.

The specific rules regarding how the reversed spell works are up to the DM. But some examples are detailed below to serve as a guide (for these examples, target refers to the target of this spell, and caster refers to the caster of this spell:

• Eldritch Blast: All beams of energy are diected at the target. The target makes the necessary number of attack rolls against their own AC. Normal additional effects are applied (if any)
• Disguise Self: The target takes the appearance the caster chooses and the spell lasts the full duration.
• Invisibility: The target becomes blinded for the full duration of the spell.
• Animate Dead: The undead servant is hostile to the target and no one else. The servant obeys the caster and tries to disobey the target to the best of its ability.
• Polymorph: The caster chooses the creature for the transforrmation, the CR of the creature is subject to the same restrictions for the original spell. Additionally, the caster can cause the target be affected by the spell instead. The spell lasts for the entire duration.
• Wall of Force: The wall appears as a dome around the target, but only the target is unable to pass through it. All other creatures are unaffected by the spell. The spell lasts for the entire duration.
• Mass suggestion: The caster chooses up to twelve courses of action with the same constraints of the original spell, the target must follow them all to the best of their ability. If the caser of any of their allies damages the target, the target chooses which course of action to forget, but the rest of them remain active for the duration.
• Simulacrum: The spell works as described, but the duplicate believes it's real and feels compelled to destroy the target, but friendly to the casterr. Otherwise the duplicate behaves as the spell describes