Let me start off by saying tank Rumble is viable, heck even extremely viable. Even with all tank items or just a little bit of AP, Rumble puts out damage. I started off playing tank Rumble and did pretty well in ranked games.

Still, I was curious about AP Rumble. With low cooldowns and good ratios, it seemed like a good idea to try. His damage is almost the best in the game from about level three to the very end of the game. Even without buying tanky items, Rumble still feels tanky. With Merc Threads and a 500+ damage shield on low CD, you can't be put down easily. Let's not forget you have up to three slows.