Hidden chimera
 

Do you need to play a wandering monster card with the hidden chimera to get the +10

Re: Hidden chimera
 

Nothing on the card indicates that you can play it without a Wandering Monster card to add it to a combat, so yes, you would still need a Wandering Monster card (or other card that allows you to add Monsters to a combat) to add Hidden Chimera to a combat to get the bonus.