Thanks
There are some rules I forgot to mention tho
If you choose to attack the coins, you roll a d12 and whatever number is on the dice is how many coins die (for weaknesses and resistances add or subtract 1d6). After a coin is dead, it is broken and worth nothing (the dm can choose to remove this rule and reward the party with gold prices after the swarm is defeated). Once every coin in the swarm is dead (a swarm can have 20-300 coins) the swarm is defeated.