So I like Morde. Hes one of my few lvl 5 Champs that isn't a jungler or support. Ever since his rework though I haven't had many good performances with him as I had previously. I'd like to take him into the Summoners rift once again, and I was wondering if you could share ideas! :D
You cant. He needs a full rework.
To elaborate, he has the same issue as Yi, Annie, and most tops including the 'high skill' ones like Riven: having a nonexistent skill or strategy requirement to access almost all of their power. As a result, they win or lose almost entirely based on team comp, and have to remain weak enough to not steamroll the rest of the game.
Ez pz. Go top, then:
Max Q
Three words: HAIL. OF. BLADES.
Secondary runes: resolve with bone plating/overgrowth
Now, for your masterpiece build:
dealers choice, but I like 
Win every game
The problem is that he needs rylais to function His abilities should already have CC
Sorcery + Resolve He works mid and bot the best in my experience. Sorcery take Aery and go down the list as you see fit, get the burn damage and celerity.
Resolve take revitalize, it helps sooooo much with your W, you can go from 10% health to like 80% from W'ing raptors. Start E, go W, then go Q. Max W then E or Q depending on how much mobility the enemy team has. Low mobility enemy team means Q, high mobility enemy team means E second.
Buy Rylais first. Do not go recommended and get the protobelt. The active is on a long as fuck cooldown and the stats it gives you are pretty worthless for the amount it costs. I recommend spirit visage as a second item as it helps with your W heal even more. After that, just build as necessary. For me, I just build damage and magic pen now.
For combat strategy it's pretty much just knowing how to get the most out of your W heal and landing your Q. As you're an imobile caster it's pretty hard. Don't be too reserved with your ult either. If you ult with rylais the slow is active for the full 10 secs. Even if your ult is on cooldown, you can still take dragon's ghost. Use it often.
A good strategy for early game is to poke them down with E and Aery. You have no mana and damaging enemies give you shield so poke away(don't forget to farm though.) Once they get to around mid health, freeze the lane. This is when you can do the burst strategy. Get 2 Qs off of minions, Flash in hit them with the last Q, E, Ignite, Activate W and if you have ult, Ult. You'll most likely kill them if they were below 60% health before the combo with ult, below 55% if not.
Start Dark Seal if you're going mid. The extra AP really lets you snowball into a scary monster.
