I recently bought Singed finally to round out the roles I can play, but most of the guides I've seen so far are still not up to date with the new masteries.
At the moment I'm thinking of 2 possible builds:
1) Going deep into Defensive to maximize my durability. Initiator will also help endgame for flinging their carries to their death. Extra points could maybe go into Expanded Mind for the mana/health, and then into Swiftness if there is any leftover.
2) Going deep into Offensive. Since Singed can become durable with his Ult and can build tanky, why not go all out AP and have your poison kill people fast?
I'm most likely going for the first option, but any inputs would be extremely helpful from long time Singed vets.