NEW SUMMONER SPELL: BUTTRESS
Would you pick a spell that got better as the game progressed instead of what most Summoner spells seem to do? Buttress would reduce your mobility for a few seconds but Increase any ARMOR or MAGIC RESIST you had built. It does not give armor or resist if you haven't built it so it would take the place of Barrier. And it keeps Tanks from going Beast mode early on but really helps on engagements later on.
Side note. Why do you think Ignite, barrier, and heal don't continue to scale with time and level. At the 40 minute mark what is 345 health going to do when you have an ADC that has 400 AD? I can't forget that one whole second of 30% speed. By level 6 heal is the equivalent of almost 3 autos from an adc. At level 18 its one.