How does Sterak's 50% base attack work with runes or buffs or items or abilities?

"Base Attack Damage" refers ONLY to your starting AD + AD per level

Anything that scales off base AD or total AD benefits. Things that scale only off bonus AD don't.

If you mean like for stuff with Sheen, the effects work together.

So if you have 50 base attack normally, sheen will normally do 50 bonus physical damage. But with sterak's it'll do 75.

• It does not interact with ANY AD from any purchased items at all. Base AD 100 plus Youmuu's = 155 AD; Sterak's only grants 50 (50% of 100).

• The AD it gives itself does not counts as Bonus AD, counts it as total AD.

• Because Sheen items are based off Base AD, this item works VERY well with champions who like Triforce, and i suppose IBG to a lesser degree.

• If my Base AD is 100 when i get this, i will have 150 Total AD (+50 through Sterak's) but ZERO Bonus AD. The AD Sterak's provides gets classified as Base AD.

• GREAT item if you like Black Cleaver, Tri, etc. Those two plus Titanic is expensive as fuck but scary strong and moderately tanky, particularly if the champ also some Dmg Reduction or shields built in.

It's only from the base AD, which is the AD a champion gets from the start of the game + what they get from Levels.

The new runes DID have a knockon effect, though. Because so many champions got +9 base AD put in their kit with the preseason, that's 4.5 extra AD from Sterak's on every character that built it, an extra 9 damage on sheen, 18 on Trinity, and 27 with Sterak's+Trinity.

One thing to note about it is that Sterak's will not switch adaptive damage from AP to AD if AP is the standard for the champion. I discovered this using Taric when my adaptive bonus switched back to AP after losing .

do you know how easy it is to multiply the base damage by 50% and test it urself?

it literally takes your base AD and you get half of that added

nothing else in the universe affects that in any way shape or form