A servant just appears from yours summoning circle.

"I am Saber, name's Mordred. Are you my master? You look weak! But don't worry you fool useless master I'm here. What would you be without me? Enough talking, let's beat our enemies ass already!"

She looks at you; her face and body are covered with her knight's helmet and armor.

Congrats you just summoned a saber class servant.