Tanks don't normally get tons of kills. Since you normally lack damage as a tank, you more so set up kills, then directly kill stuff. In terms of a build, here's one. You lose with this, its completely your fault this build is excellent.
AP/Tank:
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Decent AP, decent resists, and a good bit of health. Zeke's is optional, and can be swapped out with a Frozen Heart, depending on the team comps. The active on Seraph's is pretty good when engaging, and picking up an early tear helps out with your pretty heavy mana costs. Do keep in mind, early game is a bit of a hassle.