As to the build, this build is offtank singed at best.
You level fling over better cc, only for damage.
You start with regrowth pendant, which A) is unecessary if you just start with Sapphire Crystal and build catalyst the protector quicker, and B) you just have it sit around till your FON. It just plain isn't a good start.
Quints of evasion are only good against AD champs that are auto attack reliant. Only a terrible carry would be attacking you enough to make these worthwhile. I.E. they're not good. You're much better off taking move speed quints, health quints, or resistance quints of any kind.
And no matter what perseverance says it boosts, it doesn't boost ****. It's bugged, just like expanded mind, in that it only works off your base stats.

No one with half a brain will chase you as singed.
Sunfire cape is stupid as **** on singed. Because how often do you stand next to people to deal damage? Not enough. You're not Garen. You're not Amumu. You're going to be running around and kiting people. It's not synergy with his poison. It's synergy with standing in the middle of people constantly.

@ThaHood. My choices as far as Rylai's and Frozen Heart are concerned are for team support. The Frozen Heart Aura helps protect you allies and Rylai's slow adds a slow to, again, help your allies. If this was an AP build yes you would want them to chase but this is meant to tank for your allies. As for sunfire, I find it underwhelming. The nerfs on it made it pretty weak and just made frozen heart worth more.

@GoD Kenshin. You'd be surprised how powerful Singed's Ult is. This is what allows you to build things like RoA and Rylai's without too much problem from ineffective health stacking. And GA is a great final item. I left the final item out of the build because too many people just look at the top to get builds so i figured I would discuss final item choice later in the guide but forgot. I will update with some other item choices at a later time.

@ThaHood has pointed out everything :( , otherwise the guide seems good ;) +1

@ThaHood has pointed out everything :( , otherwise the guide seems good ;) +1

Why you take Rylais? It's a quiet expensive item for what it brings you. The slow is something you don't need, you outrun everyone already and you want them to keep chasing you. With this slow they will be more likely to stop chasing you.
I personally prefer a sunfire over frozen heart, this of of the synergy with with poison.

Other wise a good job

Nice build and explanations. Still im not sure if that build makes you tanky enough to be the main tank. I think ill try it out. What do you think of grabbing a Guardian Angel as the last item?