After the loss of Aiur the sacred shrine that was dedicated to the creation of the dragoons [...] was infested by the zerg and lost along with the protoss homeworld itself. The remaining dragoons have become the immortals, refitted with turret carrying twin phase disruptors and 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.[1]

Due to their shields, Immortal can be deployed into the battle even with extreme method - drop from the shuttle [...]. The ratio between the weight and air resistance ensures quite low maximum free fall velocity thus the impact on the ground is comparable to a hit by tank cannon. The Protoss inside the exoskeleton protected by dampers can easily withstand short-term gravitional overload in tens of Gs. Immortals dropped from flying shuttles can cause mass destruction among the enemy positions.