I want to play my Joker, but I haven't come up with a good strategy yet.

It's real easy. It's called LAMP (Lockjaw Armor-piercing Mastermind Poison). Put Armor-piercing on Joker and carry him around with Lockjaw. Remember to either outwit your opponent's outwit or put Joker in hindering terrain so his Mastermind can't be outwitted. Siphon damage to Lockjaw with Mastermind. A good LAMP team is almost a guaranteed win.

I take it you mean the Icons booster-version and not the Icons Starter-set version. My suggestion is to make sure you have a pog included in your build for Joker to Mastermind his damage onto. Or 2 . Or 3.

Choose a pog that has a reasonable speed so it can keep up with Joker, or move Joker less than his speed rate so the pog is always adjacent.

200 pts
Joker (icons exp)
Ra's al Ghul (icons u) + Laz Pit + Auto Regen
keep ' em adjacent and in stealth
this is rediculously hard to bust