Lancer of Red

One of the Servants of the “Red” camp. One of the great heroes that appears in the Ancient Indian epic poem, the Mahabharata. His true name is Karna. Since details about him have already been revealed in Fate/EXTRA CCC and the material book Fate/EXTRA material, I will only write about Karna as concerned with his appearance in Apocrypha.
In the Great Holy Grail War, Karna is the Heroic Spirit who didn't acknowledge Shirou Kotomine as his Master right till the very end. He continued to serve the Masters whose consciousness had been stolen until the end. He merely obeyed Shirou out of necessity in order to protect them; if it weren't for that, he would have been an aloof Servant who would merely obey his Master's desire to “obtain the Holy Grail.” He truly is a saint, although I get the feeling that, after having served with such an honest and faithful attitude, he said in the Moon Cell, “Then, this time I'm put together with a completely useless shut-in of a Master,” but who knows?
This time, he had an abundant mana supply, so he was able to utilize his full power at full throttle, unlike anything seen previously. Honestly, I feel regret over maybe having gone too far with him. He acts as if damage is nothing to him thanks to his golden armor, he sends the enemy flying with his “Mana Burst, he's covered in flames like a burning phoenix, and his divine spear releases a humongous explosion—in contrast to his modest attitude, it gave the impression that he was rampaging violently.
He possesses power and skill that isn't inferior to that of Achilles within the “Red” camp; truly a case of two star players in a single team. During the great battle in the second volume, Lancer of “Black”'s repeated attacks weren't half-hearted at all, and any other Lancer besides Karna wouldn't have been able to withstand it.
Karna saw in Siegfried in the face of a pure warrior trying to carry out his duty even while feeling anguished by something. It seems it was similar to what he saw in the legendary bowman who he fought in the past.
Also, originally in the Jumbo Jet Counter-Attack battle of volume 5, there were plans to have something like a “Massive Jumbo Jet Target Shooting scene where Karna readies himself and sticks his spear in the ground, and when Semiramis asks what he is doing, he says, 'Weapons are unnecessary. A true hero kills with his eyes!',” but it was too much of a ridiculous gag and it ended up being cut.

Fate/Apocrypha material: Fate/Apocrypha Encylopedia