Mythics are a weird topic when it comes to Singed, as Singed doesn't use many mythic very well. Riftmaker give some nice sustain, but the true damage is negligible and the sustain isn't all that great. Turbo Chemtank is good for tank Singed, but now you are just a fling bot. So here is my person opinion on each Singed mythic.

Riftmaker is a popular choice that looks good on paper. In actuality the sustain is not good and the passive doesn't do much, but if you like the stats this is a great option.

Everfrost is lovely if you want stats. Also pretty broken in the current patch, this item also has a ridiculous active that means you can chase people or run away with easy. Also lets you setup good Fling combos.

Turbo Chemtank is by far the best tank mythic for singed, and synergizes well with Dead Man's Plate. You don't do much damage with it, but throw in a Rylai's Crystal Scepter and you'll do enough.

Liandry's Torment is the best for oneshot burn Singed. It punished people really hard if they get hit by Fling into Poison Trail. It also clears waves really fast. Make sure not to get hit, you are really squishy with this mythic.

Hextech Rocketbelt gives a fair bit of movement speed on its active, and the active does a small bit of damage. Feels pretty good, but the magic pen is negligible at best and it doesn't have any utility.

Imperial Mandate is there. It's an option. It's only really good if you need a cheap build to avoid being embarrassed about being 2 items at 25 minutes. It may get better in the feature so I'm keeping it here.

This is a question many new Singed players ask, but there isn't a great answer and there never really will be. Singed is similar to Shaco in playstyle with the fact that it is not similar at all. They kits and playstyles are like no other.

Personally, I got good at Singed after some 400k guy who hadn't played for a year whooped my ***. It just kinda clicked. I'll do my best to explain what I do here.

Laning on Singed is interesting. You will want to be pushing every wave unless you are getting bullied or waiting for a gank. You're main damage is using Fling into Poison Trail in your minion wave. This can force many champs out of lane level 2 if you remember to Auto-Attack. If you can crash wave level 2 so it pushes towards you it is extra effective. This damage will catch many people off guard, and you can get and early kill with Flash or Ghost with Ignite, assuming you took Ignite. Your roams are kill on Singed, so if you see your midlaner is in need, try to clear vision and roam down river, which works especially well with Predator.

Proxy Singed is even weirder. Level 1 proxy is not something I'd reccomend, it is very easy to die, but if you pull it off and have Future's Market, you can come back to lane with a Doran's Ring and Boots, if you started Corrupting Potion.

This is where I'll put some item's that I'm experimenting with, and you may like.

Gargoyle Stoneplate is an item that works well with the health from Rylai's Crystal Scepter and Demonic Embrace, as well as Morellonomicon. The shield is nice to have in fights where the enemy team has burst, and stats are nothing to joke about.

Sunfire Aegis is an interesting idea for first item. If you take Conqueror and auto attack a lot, this could be a really good item to try.

Cosmic Drive is a for fun item that could be interesting, especially with a meme build where you take Night Harvester, the ability haste could give some nice speed. Might be viable at some point.

Added notes that there is no longer a consistent way to win the Yorick matchup.

Moved Teemo up to major threat because of his buffs.

Added Yasuo because after his buffs he will probably be better top than before.

Other than these matchups, the lane for Singed has not changed very much at all, other than to be more aware of Trinity Force users.