Mordekaiser is a super strong mid game champ who scales well into the late game. While he has less snowball potential than say a Darius he is Safer in the lane since he can cs with a long q range and sustain with his w. Mord is one of the strongest team fighters and objective controllers as he can take an opposing champ out of the team fight.

Mordekaiser is really weak before his first back and lvl 6. You lose against most champs early so just let them slow push into so you can poke + hold a freeze with your q. Once you get you first back and lvl 6 you can 1v1 almost everyone as long as you hit your qs and e.

Once you enter the early-mid game look to get lane priority so you can TP for objectives bot side and help in team fights. At this stage of the game Mord can really carry team fights and he can ult the enemy jungler when they try to contest drake.

Late game as Mord you can split push and look to create 5v4 team fights for your team with TP. Full build Mord does a ton of damage and is tanky AF, however some champs do start outscaling you such as Fiora and Kayne. Always think about who you should ult in a teamfight and who you can beat in your ult.