Geargrinder is a Void affinity rare from the Ogryn Tribes faction. Geargrinder was added to Raid as part of the legendary fusion event for the High Elves champion Pyxniel.
Geargrinder really only has 1 place where he is an MVP, Faction Wars. He is the only reviver in the Ogryn Tribes making him valuable to complete all of Faction Wars with 3 stars on each level.
He can be a solid support champion in any Dungeon as a healer / reviver.
I do not think you would need to take him past level 50 or invest in masteries past tier 4.

Attacks 1 enemy. Places a 7.5% Continuous Heal buff on this champion for 1 turn if this attack is critical.
Level 2: Damage +5%
Level 3: Damage +5%
Level 4: Damage +5%
Level 5: Damage +5%
Level 6: Damage +10%

Heals all allies by 15% of their MAX HP.
Level 2: Heal +5%
Level 3: Heal +5%
Level 4: Heal +5%
Level 5: Heal +5%
Level 6: Cooldown -1
Level 7: Cooldown -1

Revives a dead ally with 50% HP and 50% Turn Meter.
Level 2: Cooldown -1
Level 3: Cooldown -1

Increases Ally HP in Faction Crypts by 25%.

PVE Masteries

PVP Masteries