I wiped a few times, but things turned around once I read through an excellent Chess Event soloing guide from WoW blogger Tikari of Tikari's Tricks of the Trade.
Keep in mind that even with a great plan, the Chess Event is still plagued with RNG issues. But knowing what to expect will hopefully keep your rage at bay.
Tikari lays out a simple set of moves -- with diagrams -- and priorities to give your king the best chance of surviving, which is the main goal. The event was nerfed to increase the delay between enemy moves, but keep a few tips in mind.
- Move your king, and queen if you can, out of the fire immediately. Fire isn't a buff!
- Attack the enemy king with your queen, using the Rain of Fire/Poison Cloud ability. Be sure to target the enemy king with the queen's main attack.
- The Clerics seem to heal the enemy king more than I remember, but I kept them distracted with other pieces.
- Medivh doesn't cheat as quickly as he did before, so you'll have time for about four moves before he does so the first time around. Be sure to at least give your king, ideally your queen as well, space to move. I was able to win in the end by moving backward out of fire, drawing the enemy king into it.