CFrame.new(p1.pos, p2.pos) * cframe.angles(0,1,0)
Does this mean that the angles z and x will = 0 and y will remain the same?
CFrame.new(p1.pos, p2.pos) * CFrame.Angles(0,1,0)
It would increase your CFrame's Y rotational value by 1 radian (around 57.3 degrees), your X and Z rotation values won't change at all.