Hardened Shields

From The StarCraft 2 Wiki

Hardened Shields is an Immortal ability that reduces damage from high damaging units, but will let the Immortal be weak towards low damage units.

Ability

The Immortal's role is primarily a tank, intended to absorb heavy damage from incoming enemy fire and reduce it all to 10 with their Hardened Shields upgrade. This is particularly useful when against the heavy hitters such as the Terran Siege Tank and Thor, Protoss Dark Templar and Archon, or the Zerg Ultralisk and Swarm Guardian.

Background

Former Dragoons, now Immortals are refitted with hardened energy shields that can shrug off the most powerful weapon strikes - though at the cost of leaving them more vulnerable to the pinprick attacks of lesser foes. The heavily armed and shielded immortals give critical fire support to the ferocious legions of Zealots by eliminating enemy artillery and ranged attackers, allowing the Zealots to close in and complete their work of destruction.