When you can't decide if you need Armor or MR

http://33.media.tumblr.com/b6f94e0f73af07f01c2dfc98e6d3ece5/tumblr_inline_o3zpfj0h871tbg0pz_500.gif

When i catch myself trying to figure out if i should build more against

this: or this:

but then there is this godly item

but then your in aram