Talk:Heimerdinger/@comment-9705522-20130730194913/@comment-1853032-20130731005042

You could be seeing an affect of magic penetration - while turrets don't correct theirselves to heimerdingers' current AP scaling (they scale off when they're placed, that's it~) They do however imeddiately benefit from magic penetration.

Do some bug-testing, try to recreate it and analyze what causes it.