Do health % runes stack with Vladimirs passive? If they do, how?

Question

There's a rune that gives you 0.5% percent bonus health. Vladimir's passive ability reads as follows:

Vladimir gains ability power equal to 2.5% of his bonus health and bonus health equal to 140% of his ability power. These bonuses do not stack with themselves.

My question is, how do these both stack together? Do you get greater health bonus for ability power? Or do you get more health except the passive which gives you more AP?

Answer 1

Yes the percentage bonus health will give you bonus AP.

If you have 1000 Bonus Health you'll get 25 bonus ability power from your passive. If you now have 2.5% bonus health (5 seals) also with 1000 bonus health, you'll have a total bonus health of 1025 resulting in an AP bonus of 26 AP (rounded up from 25.625).

Note that bonus health means health from Runes, Masteries and Items. Your base champion Health is ignored when it comes to these calculations meaning that flat Health marks are usually stronger.