Hi it's whybother34 the silver 4 support main who you really shouldn't read their guide on Leona or Braum that I made. Those were my number 1 and 2 support respectively so it's time to make my guide on Morgana my number 3. Morgana is a great support who's ability to lock down single targets with her q and teams with a well done ult, combined with her e's ability to make your adc or whoever you put it on unable to be cc'ed or 1 shot by syndra makes her a great support. However her passive and w lack much value in the support role besides w's ability to get spellthiefs stacks and proc thunderlords.

Passive/Soul Siphon- Morg gets spellvamp. Does almost nothing in a support role unless you build a lot of AP. The heal will also only really come from your q the only single target spell.
Q/Dark Binding-A 2 second root at level 1 up to a 3 second root when it is maxed. Combine that with very high base damage and a 90% AP scaling makes this ability hit hard and guarantee most people's deaths late game
W/Tormented Soil- An area of damage appears and lasts 5 seconds doing about 0 damage scaling with 11% AP. Damage increases by up to 50% based on enemies missing health. Low damage execute that is weak besides getting spellthiefs cash and procing thunderlords.
E/Black Shield-Put a magic shield on an ally and they can't be CC'ed for the 5 seconds the shield is up or until it breaks. With a 350 magic damage shield at max rank you can prevent your adc from almost anything. And not being able to be CC'ed is beautiful icing on the cake. Doesn't work well against an all ad team unless they use a lot of CC.
Ult/R/Soul Shackles- Enemies in a large circle around Morgana get a chain attached to them dealing medium damage + 70% AP scaling and are slowed by 20% for 3 seconds. If morg stays within range of the enemies for 3 seconds, damage is dealt again and they are stunned for 1.5 seconds. Up to 600 + 140% AP scaling to 5 enemy champs makes this an incredible spell for engaging with a slow and then stun. However positioning while doing this is key. Now enough rambling I'll move onto the actual good stuff.

Start with spellthiefs like any other damage type support and get your q first. Some people like getting W so they can get the spellthiefs cash earlier but I don't do that incase someone tries to invade you would rather have your q or if someone gets caught out in the invade get your e. Level 2 is difficult to decide what to get if you got q first. I generally go e if they have engage and you need to be able to black shield your adc from the cc. If they have say a sona and a mf you can get your w for the cash because they don't have any hard cc until later. Once you hit lvl 3 go and try to root the adc (or support if they are out of position if they are a tank or anytime if they are squishy). The mana regen runes are going to be changed soon but with these I don't feel a mana burden when casting my spells so I can do what I want. Note Only black shield if necessary don't do it for a soraka q save it for her e. The cooldown is quite long at early lvls (23 seconds to be exact at lvl 1 and it will stay that way until lvl 8) so be sparing with the usage. Once you get cash back and get the frost fang a sightstone and maybe boots. Once you hit 6 use the ult generally as a counter engage when everyone dives you. You can flash and dive yourself but know without zonyas they can just focus you down and if your adc doesn't have cc they could just get out.

more to come later
Update 10/24 Put in abilities description
Update 10/27 Early game