Okay!!! here's my opinion.
Protect: Your champion gains 30 (+5 per level) magic resist and armor for 2 seconds. around 200s cd.
The short duration makes tower diving hard but also possible, but it still is going to take skill. But if you can burst someone down in two seconds then you could probably tower dive without this spell...
Protect would give your champion a good buff for a short duration making it take skill and good reactions to time it with the high damage spells thrown at you. The extra 35 armor and mr early game could save you from an annoying blitz grab in an early level 1 fight or give you the upper hand in a 1v1 or 2v2. Come end game 120 armor and magic resist is a lot but is still countered by a void staff, last whisper or ignite.
If your worried about dps champs destroying people with this "op" spell then ask yourself how much dmg can most champs do in 2 seconds? And how bout you ask you friendly neighborhood sion to throw a quick stun on the champ? Once the 2 seconds is up the champ would be in a bad position and likely be able to be focused.
The purpose for this spell should be solely defensive. It's main use is to get out of sticky situations or survive large bursts like karthus, veigar or lux ult. You can still be stunned while it's active and the short duration makes it's use of an offensive spell almost null and void >_<.
Why choose over other defensive summoner spells?
Flash. Flash can't be used while stunned or snared making you susceptible to high amounts of dmg. Protect would allow champions to survive being stun locked and allow them to survive ults and other high dmg abilities that flash can't do anything about (karth ult, malz ult, cait ult, ww ult, etc)
Ghost. Ghost lets you run away! But running aint gonna do **** when ez, karth or lux ults ur ass from across the map. Protect once again allows you to survive these large bursts.
Heal. Heal may save you from large bursts if you already have lots of mr and armor but it can't really help you when your stun locked or being focused in a team fight.
I like this idea because it will take skill.... Something a lot of people are lacking in this game. Rather than flash or ghost, protect is not gonna insta save you if you don't know how to use it. With flash you can just disappear from a gank... Protect would need to be saved for a certain moment in order to reduce the main burst dmg. Protect however is much more beneficial in team fights since it can save you from being stun locked or from a huge burst of dmg.
I just think riot needs to quit making so many champs and expand the game a little bit. I could see this being a huge spell once the 7v7 map comes out (if its 7v7 idk) for the same reasons as on a 5s map.