Why are you jungling rengar :s he's a much better top lane. He's basically a shaco as jungle, can't keep up if he doesn't get kills. And unlike shaco, rengar gets stopped by wards and has pretty poor clear time.
Oh and also, I am usually a higher pick so I get countered everytime I go rengar top
Who is a better mid between fizz and diana? I really like dealing burst damage in combos
The answer is none of the above. Morde gets outclassed in practically every way by other champions. He has no cc, low range, has low base stats, average ratios, and gets gibbed with any form of cc. The only way he's ever effective is when the enemy team decides it's a good idea to group up on top of each other. And even then, it will mean nothing if you can't instantly gib somebody you ulted. If anything, he's a piss-tier clean up champion, outclassed by actual cleanup champs like Kha, Kat, and Yi.
"1) Mordekaiser is perfectly Viable, both as a Top and a Mid, though he's got a major weakness in both his lack of escapes and the fact that he can be CC'd pretty hard since he's not the best with range. That said, if you've got a team that can really murder the AD carry and get your ult off with that, Morde can carry the game with a Ghost."
Had to take this from a forum post because I couldn't really put it in my own words as well as someone else. While he is very weak because of mentioned lack off CC, his vulnerability to CC and lack of range, his ghost is just too strong to ignore. If the person playing Mordekaiser is smart, you can easily get lane advantage against many champions simply by playing smart, taking wraiths to get level advantage etc. His ghost is the strongest thing about him because of how well it scales off of fed opponents if you take their items into account and the fact that on hit items actually work. (botrk anyone)
If you're planning on playing Morde at a competitive level I would definitely get some practice first because, as Oracle said, he can be outclassed by many champions if you don't know what you're doing and sometimes even if you do.