Tactics
Gilgamesh battles by shooting the originals of all Noble Phantasms like bullets via Gate of Babylon. The tactic yields excellent destructive power to magic energy efficiency. Since every Noble Phantasm is a bullet, the real magical energy used is merely the activation cost of Gate of Babylon. Because he possesses the originals of all Noble Phantasms, he can assault the weakness of any Servants. As a result, Gilgamesh has the advantage over most of the Servants in combat.
Because he has absolute self-confidence, he is able to calmly show himself before his opponents. However, depending on mood, he is also fine with scoring kills by raining Noble Phantasms behind the enemies’ back. The will of the king cannot be simply gauged by the concept of tactic.

Fate/complete material III; Servants of the Fifth Holy Grail War, pg. 24-25