Spellbook Ornn on support is a fun to play pick, that can do a lot of things.
Your role is to be a playcaller, you survey the map and look for good picks to do and plays to make, then try to make them hapen. You bring great CC and frontline to your team along with good engage (R)
Spellbook allows you to make creative (or even crazy) plays, like contesting both dragon and grubs at the same time or ganking top via TP

+ Insane playmaking potential
+ Works well with most ADCs
+ Friendly aura
- Poke comps make him unplayable
- Needs a working team
- Comunication is a must

During laning phase, you defend your adc and try to hit your Qs. Level two you can give knockups and walk away basically unscathed. Level 3 all in becomes possible.
You try contest dragon whenever possible and if you know the enemies are going for it, swap smite as either first or second swap. If you decide to go for steal, knockup jungler right before dragon reaches smite threshold and steal. (i did it 3 times and enemy jg can be very vocal about it)
You rush boots as these allow you to survive in lane very well.

Two things happen:
a) ADC is fed: You play as if you were on top
b) ADC needs you: you follow it and help it get more strong
After laning, you try to help in whatever way you can do it
- Are you near a wave of enemy minions? push them and leave
- Is dragon spawning soon? setup vision around it
You basically allow your team to do things safer by getting prio in lanes and vision.
Also upgrades give your team total of 5000g worth of stats

Your W can block any hook, as it comes with short unstopable.
You can knock up adc then walk away, they cannot retaliate withou following you
Your W's effect extend incoming cc by 1/3. So morgana Q for 4 sec - Yippee

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Example Plays
Taking dragon and grubs at the same time - Jg goes grubs, you and adc go dragon. You take smite for securing.
Top gank - You tate TP and gank top. Nobody expects support to show here so you might give your top a free kill if executed right. (caught few toplaners of guard already)
1 wave push - Push one wave if you end up near it, sending minions deeper. Doing this past level 9 is almost instant.

I main this unusual build and find it lot of fun to play. Works best when your team cooperates (or even better if you play in a group). If you decide to play it, be ready that first few games you will probably end up usefull as afk jg.
But the moments it works are worth it.