So I was looking at Sterak's Gage and it said Passive: +30% Base attack damage and +40% when Sterak's fury is activated. I was wondering what's the difference stat wise? Does it not apply to certain skills? I'm a bit confused
Let's look at a champion with 50 AD that owns a long sword. That long sword gives 10 AD, which makes their new total AD 60. If they were using an ability that scales 100% Total AD, that ability would do it's base damage plus 60 damage (100% of the total AD).
If it scales 100% bonus AD, then it would deal the combined damage of all of the sources that gives you AD (Runes, masteries, items, buffs), but NOT counting your base AD (What you have WITHOUT runes, masteries, items, buffs). In this case, if we look at it in a vacuum with just the long sword, the ability would deal it's base damage, plus 10 damage (100% of your bonus AD, which in this case, is the 10 AD from long sword)
Therefore, if you have 50 base AD and an ability scales with 20% of your base AD, the final scaling would be 10 ( 20% of 50)
if you move your mouse cursor over your attack damage stat on the character panel it will give you 2 numbers. 1 will have a + symbol next to it. that's your "bonus attack damage" the one without the plus symbol is the base attack damage. that's how much attack damage your champion has without ANY items, masteries, or runes.
so steraks is only useful on champions with high stats regardless of builds.
Your base attack damage is your champions scaling number that does not include an AD items, while total attack damage is the addition of base plus any items that grant additional attack damage.
Base attack (and base stats) are all of the stats you are guaranteed to have and are before items/runes/masteries
