Iron Skin and Mirror Shell runes seem totally pointless

+3 armor/mr and 5% for 3s after you heal for either 20+ or from a consumable. I'm assuming that means you get this 5% as long as you have potions ticking, which is good mechanically, but 5%? Is that going to make any difference early game when you have potions and you specced this for your lane matchup?

I mean if you have 50 armor/MR you get 2.5 so in that case you're getting 5.5 total from the mastery.

I think I'd rather take Conditioning even if it's a difficult lane matchup. I'd rather tough through it and have both armor and MR later, especially because later on I won't have a slot for potions so I won't get to use the 5% unless my champion can heal itself.

Maybe Iron Skin and Mirror Shell should have the numbers reversed. Flat bonus after heal, % bonus passively. It would let these masteries stay beneficial later in the game when you can't fit potions anymore, and also be higher impact during potions early game.