(NAME NOT DECIDED) The Phantom Guardian.

CONCEPT: "Ghost of knight/Posessed armor" Tank/Assassin. Wait what? Yes, TankAssassin, the idea is to show up out of nowhere inside the enemy's backline, jump their marksman or mage, and shrug off attacks while the team shows up.

Passive: Wraith: Can attack while moving and move through units. Q: Ethereal/Corpreal Form: Switches between two forms, Corpreal Form is more vulnerable to physical damage, while Etheral is more vulnerable to magical. W: Undying Purpose: Passively increases Tenacity, Activate to generate a shield that absorbs a portion of damage taken, then releases it when the duration is up. E: Fearful Symmetry: All debuffs applied to self are also applied to the target of Fearful Symmetry R: Vendetta: Goes into stealth, upon breaking stealth with an attack, target is marked, While chasing and attacking marked target, gain movement and attack speed respectively. Attacks deal bonus damage based on target's AD and AP.

Gameplay would likely be picking a form more suited to the following teamfight (They have more AD? ethereal form, the mage is fed? Corpreal form). Then going vendetta, Jumping on a target and popping both Undying Purpose and Fearful Symmetry and wailing on them while your abilities make any "helping" CC from their allies affect the target, while you shake it off with superior tenacity and a portion of damage dealt will be dealt back, and as thus, is better when his target's in a group as opposed to normal assassin methodology.. Without ultimate, he acts more like a traditional tank, standing infront of his team and using abilities that help him tank damage while retaliating.