I have Ember Monk and Mutated Mouser on my board, I play Switcheroo from Hidden on my Ember Bonk and Mouser, what are the final might totals they have. Is it 1 Ember Monk 6 Mouser, or is it 3 Ember Monk and 4 Mouser. Essentially what resolves first, is it the Switcheroo or Ember Monk proc?

Based on the rules and FAQs for Riftbound, here is how your situation resolves.

The Ruling

Switcheroo resolves in full first, swapping the Might values of the units. Only after Switcheroo has finished resolving does Ember Monk's triggered ability go on the chain.

According to RiftJudge FAQ #1468 and #3381:

1. Switcheroo resolves fully: This performs the swap of current Might values between Ember Monk and Mutated Mouser.
2. Ember Monk's trigger occurs: After the spell is fully resolved, Ember Monk’s "When you play a card from [Hidden]" trigger is placed on the chain.
3. Trigger resolves: Ember Monk gains +2 Might.

Calculation

To determine your final totals, we look at the state of the units:

• Ember Monk (Base 4): Initially 4 Might.
• Mutated Mouser (Base 1): If it has Shield active (as a defender), it has 3 Might (1 base + 2 from Shield). If it is not a defender, it has 1 Might.

Assuming they are at the same battlefield and Mutated Mouser is a defender (receiving the +2 from Shield):

1. Before Swap: Ember Monk is 4 Might, Mutated Mouser is 3 Might.
2. Switcheroo Resolves: The Might values are swapped. Ember Monk effectively becomes 3 Might (from the swap), and Mutated Mouser becomes 4 Might.
   • Note: The Shield keyword is a passive ability, not a trigger; it continues to apply its +2 to the Mouser after the swap.
3. Ember Monk Trigger: Ember Monk's trigger resolves, adding +2 Might to its current total of 3.

Final Totals (if Mouser is a defender):

• Ember Monk: 5 Might (3 from swap + 2 from trigger)
• Mutated Mouser: 4 Might (effectively holding the swapped value while maintaining its Shield bonus)

If Mutated Mouser is not a defender:

1. Before Swap: Ember Monk is 4, Mutated Mouser is 1.
2. Switcheroo Resolves: Swaps to 1 Might for Ember Monk, 4 Might for Mutated Mouser.
3. Ember Monk Trigger: Ember Monk gains +2 Might.

• Final Totals: Ember Monk 3 Might, Mutated Mouser 4 Might.

Sequence Summary:

1. Switcheroo is played from [Hidden] and enters the chain (resolving immediately as it is a spell being played).
2. Switcheroo's swap effect fully resolves.
3. Ember Monk's triggered ability is placed on the chain.
4. Ember Monk's ability resolves.

Disclaimer: This is my interpretation based on the mechanics of "play" vs "played" and the referenced FAQs regarding Switcheroo and triggered abilities. No official FAQ exists for the exact combination of Ember Monk and Mutated Mouser, but the priority of resolution is standard for Riftbound.