Flat vs Scaling Magic Resist Gylphs

Scaling MR glyphs become more effective than flat MR at level 9. Taking scaling MR runs the risk of getting pooped out of lane by some champion with high early-game base damage, low cooldown abilities before that point.

3 flat 6 scaling usually myself. Scales between 35 and 52 MR.

Magic damage is not only significant late game, especially for mid laners who'll be blowing each other up at 6.

Flat because runes are for early game not late game.

Scaling MR Glyphs surpass flat MR Glyphs by level 10, which is pretty late.

I generally take Flat MR Glyphs on most pages (except for jungle-only pages and a few with CDR) on all of my pages. I might not always need the Flat MR in lane, but it makes the page more general and I suffer less when I have to lane against LeBlanc or Rumble.