Today will be a rather brief article about casters. The main theme will be magic penetration, which will be abbreviated from here on out as MPen.
With the introduction of Rabadon’s Deathcap, it’s plausible for casters to reach obscene amounts of ability power now, exceeding 500 if a caster is fed (and he won’t even need Mejai’s Soulstealer!). If you see an 800AP LeBlanc run up to your, what’s your first thought? I’m going to have to go with “Oh, shit.”
Yet let’s say that she’s got a Rabadon’s Deathcap and multiple Archangel’s Staves. With all that AP, she’s still only got around 30 magic penetration from her boots and runes – less if she doesn’t have these.
Whenever a person sees that the majority of the damage they took was from a caster, especially burst casters like Annie, Ryze, or Veigar, they go out and buy magic resist items. Regardless of whether you’re a tank or a carry, a good player will adapt his build to counter his enemies. Say you get the most logical choice – a Banshee’s Veil. That’s 50 magic resist right there (I won’t even talk about the bubble).Say you play a typical 30 magic resist squsihy champion. Against a mage with typical 30 magic pen, you have 0 MR and are now taking the full brunt of their abilities. Yet with one Banshee’s Veil, that 50 magic resist negates a good 33% of their damage. Buy an Abyssal Scepter after that and half of their magic damage is down the drain.