Serpentine Spy is a powerhouse in Fire... if it can stay alive.
Boasting 2 attack, 3 speed, and the Opportunity ability, the Serpentine Spy can be quite the ally and give you the upperhand in a battle.
However, the Serpentine Spy has a weakness... it doesn't have any armor, and it only has... 1 HEALTH!
You can be certain that your opponent may chose the Serpentine Spy as well, so in this case, the battle can be determined by who moves first.
Does this mean you should use a monster that slows the speed of your other opponent?
That's a good idea, but not fool proof.
It's, in fact, better to add a monster to your line-up that also has 1 health.
Enter the Chaos Agent. The Chaos Agent has no attack, and also has 1 health. His sole purpose is to act as a buffer.
Remember the rules for the Opportunity ability:
"May attack from any position, and will target the enemy monster with the lowest health."
If you don't put a monster in your line up with the same health as your Serpentine Spy, then say goodbye to your powerhouse early in the battle... and unless the rest of your team is uber strong, be prepared to lose.
So take note, just remember to add another monster to your line up with 1 health if you add the Serpentine Spy to your line up.
Good luck.