[Champion Concept] Terra, The Terrain Manipulator

So I am not all technical with how much damage each of her moves would do so you guys have to help me with that but I've always loved the idea of a Champion who could crush other champs with boulders or rocks etc. kinda like a malphite but not really. I just have a little idea i wanna share :)

P:Ricochet: When Terra's life is below 30% she encases herself in rock adding a shield. Every time she is attacked with the shield on, her opponents attack ricochets dealing a portion of the damage back at them.

**Q:Earth Shards **Terra casts a line of rock shards from the ground dealing ////_ magic damage in an area and slowing all enemies struck by 15/20/25/30/35% for 2 seconds.

W:Graveled Fists Terra encases her hands in rock and does additional damage on an enemy with her basic attack lasting 7 seconds. If used with passive, she gains additional shield life and ricochet delivers more damage back at the enemy.

**E:Crushed ** Terra stomps on the ground creating two boulders. After a short delay, they crush whatever is in between them dealing ////_ magic damage.

R:Earthquake Terra smashes her fist into the ground creating a circle of destroyed surface around her knocking enemies back doing a deal of damage. If any enemies walk into the circle of destructed ground they are slowed and will continually take damage from the rugged terrain. If used with "Graveled Fists" the distance of the quake increases in range.

So its a basic concept and I know its not great with damage and magic percentages with each move, but its just idea that I hope you guys like. Give me feedback on what could change and how to make her better.