Can we spawn the Wither

Both withers and beacons are disabled on lolnet. Also, Even if they were not to be disabled, Its highly unlikely the staff would spawn you one.
Although ocasinonally at events Schnicks_NZ or some other staff may spawn a wither. Events are like Mob-Arena, Schnicks Hunt etc.

Beacons can be won at events like drop party that is going to occur today at 3pm NZT. Or you may be able to buy beacons later from the LolShop.