Therazane by Egregorious

Close Family
While near Ozruk, Therazane also gains 300% extra health regeneration.

Big Hug
Increases the radius of Mothers' Embrace by 30%

Enriching Minerals
The secondary tremor of Rocky Upheaval now also heals Ozruk for 110 (+29) health.

Rock Block
Periodically reduces the damage received from Hero Basic Attacks by 35%. Both Ozruk and Therazane store up to 2 charges. 

Crumbling Defenses
The secondary tremor now deals 70(+15) damage.

Rock Polish
Increases Ozruks movement speed by 10%

Unsolid Ground
Each enemy affected by Earth Tremor reduces it's cooldown by 1 second.

Family Ties
Ozruk taking damage increases Therazanes mana regeneration by 20% for 2 seconds, stacks 5 times. 

At the Stonemother's Call
Activate to turn Ozruk into a boulder, he then rolls back towards Therazane's position with an initially slow acceleration, ignoring collision.

Therazane's Mercy
Reduce the cooldown of Stonemother's Bosom by 0.75 seconds for every 100 (+20) damage taken while active.

Skipping Stones
Therazane can now autoattack enemies that are within 75% ability range and near Ozruk.

Clingy
Activate to drain Ozruk for 4% health and restoring 3% health and 2% mana to Therazane every second for 10 seconds. 

Stonemother's Wrath
Charge towards Ozruk's position, dealing 75 (+5) damage and knocking back enemies in the way, upon reaching Ozruk, shatter and deal 320 (+ 21) damage to the nearest enemy hero and stunning them for 2 seconds, while rooting other enemy heroes nearby for 1 second.

Wayward Child
Causes Ozruk to take 75% of damage directed at nearby allies instead for 5 seconds, ignoring the damage diversion of Earth Elemental. If Ozruk dies during this time, the cooldown of Earth Elemental is reduced by 50% and Therazane appears at his death location, rooting all enemies in a large radius for 1 second then slowing them for 40% decaying over 2 seconds.

The Stone March
Increases Therazanes ability range by 30%

Entrenched
Increases the shield of Stonemother's Bosom to 25%

Spell Shield
Upon taking Ability Damage, reduce that damage and further Ability Damage by 50% for 3 seconds. Can only trigger once every 30 seconds.

The Very Earth Beneath Our Feet
Increase the damage of Rocky Upheaval by 30%.

Bad Winterveil Gift
Stonemother's Bosom now effects all allies within Therazanes ability range (alternatively, globally)

Imposing Presence
Enemies that attack you have their Attack Speed slowed by 50%.

A rock Amongst Many
Increase the damage diversion of Earth Elemental to 35%

Binding
Mother's Embrace also grants a shield to Therazane for 50% of the damage she inflicted to enemies for 5 seconds.

Between a Rock and a Hard Place
increases the speed of Therazanes charge by 25%, the damage caused by shatter by 25% and the number of maximum enemies hit by shatter by 2.

Self Sacrifice 
If Ozruk dies during Wayward Child, he also explodes dealing 30% of the damage taken to nearby enemies.

Hearty Meals
Increases Ozruks maximum health by 40%.

Storm Shield
Activate to give all nearby allied Heroes a Shield for 20% of their max Health for 3 seconds.

- Earth being a most durable element and therazane being a motherly, protective sort, I thought a tank role would suit her fine. The tank role often revolves around some combinations of initiation, disruption, damage absorption and peel. Since Therazane is the motherly type, I thought it would be best suited if she shielded those under her protection, while dealing slow, solid amounts of damage and stunning and rooting enemies as an earth elemental would. 

- Had I considered Therazane earlier, she maybe would have been a better candidate for support considering her peaceful nature, but earth lends itself so well to the sturdy tank archetype and she probably wouldn't go around willfully healing fleshy mortals anyway. Then again, neither would Al'Akir, but Al'Akir seems to conduct himself honourably, so maybe he would out of necessity. 

- I think one of the most useful skills for a tank is to get in close and body block opponents, so Therazane was given a summon with the aim to do just that.

- Considering Therazane essentially has two health bars, I didn't think she should be extremely tanky. However, since both her heroics revolve around getting her into the fight, she couldn't be too squishy either. I think maybe low starting health and high scaling health balances out her multiple health bars but inability to dodge, however I could be very wrong.

- Ozruk was originally Princess Theredras, which I think made more sense thematically, but her name was too similar to Therazane and seemed confusing. Ozruk was the closest more popular character which Therazane directly describes as a child I could find. Alternatively, Earth Elemental could summon a random Stone Lord instead.

- Therazanes "ability range" doesn't actually affect any of her abilities directly, but I'm too lazy to come up with another way to describe it.

- It actually seems a rather important thematic point that Therazane not have any abilities that would seem to agitate or destroy the earth, like Thralls Sundering or Sonya's Seismic Slam, since she appreciates the calm and resents anyone who upsets her domain.