Orb (Guardian At The Gate)

A mysterious purple orb of energy once appeared out of H. P. Lovecraft while he was working in his study, first appearing as a "whirlwind" or "storm" before entirely engulfing him and flinging him through time. After having visions of many terrible eldritch creatures, Lovecraft, still encased in the orb, exited through a rift on Tower Bridge in the 21st century. Crackling with energy, the orb dealt significant damage to the bridge itself, and killed several unfortunate drivers by blasting their cars, before it allowed Lovecraft to exit to find himself face-to-face with P.R.O.B.E. director Giles. With the orb no longer shield him, he later had to use a specially-sourced device to safely pass back through the rift to return to his own time. (AUDIO: Guardian At The Gate)

Behind the scenes
The description of this orb is reminiscent of the purplish, translucent orb which engulfs the Doctor's TARDIS in the Seventh Doctor's title sequence. This effect has never been seen in an actual in-universe source.