Tank Mordekaiser is good for a number of reasons.

1. You can build pretty much full tank and still do lots of damage.
2. You become an 1v1 machine as no one can kill you so you can remove enemy carries from the fight.
3. Your W scales with health and is a ridiculous size once your lvl 18

Tank Mordekaiser is easy there are some simple steps

1.Play fairly safe in the early levels getting as much CS as possible
2. Once you hit level 6 and get your item rush aim to take short trades utilizing grasp and then all in with R when you see an opportunity
3. Snowball your lane by zoning your enemy laner and killing them if they dont respect you.
4. Move around the map and try to shut down any fed enemy carries with your amazing 1v1 potetial from your R.
5. Splitpush and provide pressure to help your team. If the enemy team come for you, you can almost always trade at least 1 for 1.
6. Group with your team for key objectives and R any enemy carries to neutralize them in team fights to help your team secure the win.

If you've read this far you might as well check out some of my other guides that range from serious builds to funny off meta picks like assassin Nasus. Thanks for your time and good luck on your tank mordekaiser journey.