Hi, I'm Xavierix and this is my build strategy for Morgana as Controller (Support).
In the next chapters we'll give a complete analysis of the champion:

1) Morgana's Statistics
2) Description of abilities
3) Strenghts and Weaknesses

STATISTICS NAME: LEVEL 1 - LEVEL 18 - GROWTH COEFFICIENT


HEALTH: 559.5 – 2089.5 - 90 (+++)

HEALTH REGEN.: 5.5 – 15.7 - 0.6 (---)

MANA: 340.8 – 1360.8 - 60 (-++)

MANA REGEN.: 15 – 21.8 - 0.4 (++-)

ATTACK DAMAGE: 55.5 – 115 - 3.5 (-=-)

ATTACK SPEED: 0.625 - 0.7875 - 0.00956 (---)

ARMOR: 25.4 – 90 - 3.8 (-++)

MAGIC RESIST.: 30 – 38.5 - 0.5 (---)

RANGE: 450 (+)

MOVE. SPEED: 335 (=)

(+/-/=) Compared with other champions, the values are above/below/equal to the average

Soul Siphon:

INNATE: Morgana restores health equal to 20% of ability damage dealt to champions, large minions and large monsters.

Dark Binding:

ACTIVE: Morgana releases a sphere of dark magic that travels in a line, dealing magic damage to the first enemy hit and Root icon rooting them.
MAGIC DAMAGE: 80 / 135 / 190 / 245 / 300 (+ 90% AP)
TARGET RANGE: 1175
SPEED: 1200
COST: 50 / 55 / 60 / 65 / 70 MANA
COOLDOWN: 11
Targeting: Direction
Affects: Enemies
Damage: Magic
Type: Single Target
Spell shield: Blocked
Projectile: Blocked

Tormented Soil:

ACTIVE: Morgana infects the target area for 5 seconds, causing enemies who stand on the location to take magic damage every half second, increased by 0% - 50% (based on target's missing health).
Tormented Soil's cooldown is reduced by 5% whenever Soul Siphon triggers.
MINIMUM DAMAGE PER HALF SECOND: 8 / 16 / 24 / 32 / 40 (+ 11% AP)
MAXIMUM DAMAGE PER HALF SECOND: 12 / 24 / 36 / 48 / 60 (+ 16.5% AP)
MINIMUM TOTAL DAMAGE: 80 / 160 / 240 / 320 / 400 (+ 110% AP)
MAXIMUM TOTAL DAMAGE: 120 / 240 / 360 / 480 / 600 (+ 165% AP)
TARGET RANGE: 900
EFFECT RADIUS: 275
COST: 70 / 85 / 100 / 115 / 130 MANA
COOLDOWN: 12
Targeting: Ground
Affects: Enemies
Damage: Magic
Type: Damage Over Time
Spell shield: Not Blocked

Black Shield:

ACTIVE: Morgana magic shields the target friendly champion or herself for up to 5 seconds, absorbing magic damage and rendering her target immune to all crowd control while the shield holds.
SHIELD STRENGTH: 70 / 140 / 210 / 280 / 350 (+ 70% AP)
TARGET RANGE: 800
COST: 55 MANA
COOLDOWN: 23 / 21 / 19 / 17 / 15
Targeting: Unit
Affects: Self, Ally
Type: Shield

Soul Shackles:

ACTIVE: After a 0.5-second delay, Morgana latches chains of energy onto nearby enemy champions, dealing magic damage. The tethers grant true sight of affected enemies and slow them by 20%.
Targets who did not leave the tether range after 3 seconds are stunned for 1.5 seconds and dealt the same magic damage again.
MAGIC DAMAGE: 150 / 225 / 300 (+ 70% AP)
TOTAL MAGIC DAMAGE: 300 / 450 / 600 (+ 140% AP)
EFFECT RADIUS: 625
TETHER RADIUS: 1050
COST: 100 MANA
COOLDOWN: 120 / 110 / 100
Targeting: Auto
Affects: Enemies
Damage: Magic
Type: Single Target
Spell shield: Soul Shackles cannot be interrupted by crowd control and will persist throughout Zhonya's Hourglass' stasis, Guardian Angel's passive, and Chronoshift's revival.
Spell shield will only block the initial damage, not the damage that occurs if the target didn't leave the tether range.
Projectile: N/A

Soul Siphon triggers from Dark Binding, Tormented Soil and Soul Shackles. The best health regeneration is obtained from maxed Dark Binding. Infact it is quite impossible to deal the maximum total damage with Tormented Soil, or to cast it on multiple champions, big minions and monsters. In any case, Soul Siphon is not an excellent ability in terms of sustain.

Dark Binding is the main ability. It deals huge magic damage and has the longest root duration at level 5 and low mana cost. You have to start with this ability to begin with an excellent attack and control, and provides a good chance for invasion with the team. Infact it is an ability for engaging the battle. If it hits the target, the allies get a kill surely, or deal a lot of damage. You can use this ability also for escaping when you're followed, rooting the enemy.
The weakness is the high difficulty to hit the target. If this ability fails Morgana is helpless and can't do anything else but only support an ally or herself with Black Shield.
It is necessary to guarantee the success of the shot. To do that you have to build Rightous Glory. It provides Armor, Mana, Health to go to the enemy with the Active, slowing him/her and have a good chance to striking. This "aggro style" requires a quite tank Morgana at the expence of Magic Damage you can deal. So, use this ability only for the root effect and not for the Magic Damage.

Tormented Soil can't be used for dealing magic damage if it is used alone and on one enemy. Infact, in the case that you cast it with the enemy positioned in middle of the soil, he/she can go out of it in about 1 second, with only 2/10 hit of Tormented Soil. If you want to increase the number of hits from this ability you have to cast it immediately after Dark Binding or use it with on multiple champions. The best ways to use this abilities are:
1) Induce the enemy to move to another area;
2) Speed up the farm to your ally, casting it on stopped minions with full health;
3) On a Champion with very low health to get a kill (but try to not ks).
The Mana cost is very high and there are no effect for mana regeration from the abilities.
Redeption and Mikael's Crucible provide the mana regeration we want with all other goods that a support must have. Max this ability for last.

Black Shield is an excellent ability for a support. It block an enemy ability, in particulat try to block "engage abilities" of the enemy and if it done succesfullty try to engage with Dark Binding to reverse the situation in your favor.
However, it has a long Cooldown. The build provides the Cooldown Reduction you need.

Soul Shackles is a good team battle ability, dealing an initial good magic damage, slowing the enemies, and if it completes, stunning them with a second damage. It is very slow, so ensure the stun effect you must be untargetable. Zhonya does what we want but we can't move the radius effect. The best way to use is:
1) If the enemy is escaping, follow him and don't use Zhonya.
2) If you're attacked, use Zhonya (you must be with the team).

Strengths

-An excelent CC Champion
-A good engage ability
-Zone Controlling
-Block an enemy's ability on an ally or herself
-Speed up the farm

Weaknesses

-Dark Binding dependent
-Difficult to hit the target
-Difficult to deal total damage from zone abilities
-Slow Champion
-No healing effect for allies
-No Armor Shield
-No CC remotion
-No Mana Regeration Effect from the abilities