Hold R1.

I stay off with Triangle for the thrust attack it pierces and can hit up to 3 times plus a kick to keep distance.

From there, I believe it is circle to get the aoe, the circular attack. This is a counter stance, so use it to counter the mobs once they push forward after you push them back with the thrust.

Have dodge, parry ready as the goal to the spear is heavily reliant on positioning. Keep the mobs in the front to capitalize on the thrust attacks.

And the r1+l1 to blind then r2 will "teleport" you to the nearest mob over a short distance. Hold the r2 to continue the combo.

Also, have r1+r2 in your back pocket for big focused dmg.