good job

No, Cannibalism is correct. Aegis and Skyfall are magic damage not physical, it does not matter what they scale off, its the damage type is the important stat. I quite like this build, but I wont rate it now. To me that one point for magic pen is far more valuable than that tiny bit of attack speed.

But its a nice build I take a hexdrinker or some other cheap magic defence a lot now, there are a hell of a lot more casters in domi lately.

Your abilities don't benefit from spell pen fyi they benefit from armor pen actually that's why armor pen is so important. also your W at max lvl does 150 damage and benefits from AP(which you dont have any of). Also I used sanguine blade for the massive damage for champs I can't burst down and the lifesteal is huge for lane sustain. you really don't need spell pen. And your ult isn't actually a damage move.

good players wont get hit by it,

You pick 1 lousy percent att speed over 15% magic pen when 2 of your abilities are magic damage.
Why would you buy Sanguine Blade when he is a burst champion and not auto attacker. He should never auto attack unless he is chasing.
Exhaust over Ignite any day for Pantheon. He need to survive that Tryndamere ult and all the other auto attackers that he can not burst down.

Sorry wrong information leads to a downvote.

Hey thanks man; I fixed it really appreciate it!

in summary said please down down vote instead of please dont down vote, testing build now tho looks good so far.