Giles' epiphany

It's strange, it's not like anything we've faced before.
It seems familiar somehow. Of course!
The spell we cast with Buffy
Must have released
Some primal evil that's come back seeking
I'm not sure what
Willow, look through the chronicles
For some reference
To a warrior beast
I've got to warn Buffy
There's every chance she might be next
Xander, help Willow
And try not to bleed on my couch I've just had it steam-cleaned.
No, wait...