I made mention that Khyber's Harvest includes a living darkness monster, and also mentioned a living magic missile. So, here are three of them. I made them all very low level since, well, magic missile is a 1st-level spell. Makes sense, and you can add them in with other low-level magic users as support (the salvo is good enough to support the level 4 human caster in Monster Manual). Quick note: I reduced the hit points of the living magic missile and living magic missile salvo by a bit, since I'm a fan of reducing hit points by a bit (and swarms really suck).
Motes are minions. They basically smash into you, and are good at zipping across the battlefield and battering into other creatures, which is what I wanted to emphasize: sentient bolts of arcane force launching themselves at targets.
Same thing as the mote, but with hit points and can knock you prone if they charge you.
This is something that I created after recalling how you could fire multiple missiles in 3rd Edition. You technically cannot in 4th Edition without the right stuff, but I still like it so whatever. Maybe I'll create a higher level wizard encounter power that lets you unleash a torrent of arcane missiles, so there.