Ok here's the quick rundown since I actually talked to Plaz:
the shooter, identified by the media was 21-year-old William Atchison.
back in 2011 Sephiroth pretended to be Plaz under the alias plaz 2.0 by posting this topic:
https://forum.blockland.us/index.php?topic=174807.0The actual Plaz, real name in the impostor topic, was contacted by Tomthegeek. Plaz told tom that it wasn't him, so they reverse searched the email in the OP and got the name of William Atchison. So whoever impersonated Plaz goes by the name of Sephiroth, aka William Atchison. (can be verified by this post:
https://forum.blockland.us/index.php?topic=174807.msg4501711#msg4501711)
Keep in mind, this was in 2011.
FAST FORWARD BACK TO RECENTLY:
Plaz left the community a long time ago and never looked back. Sephiroth however was still friends and a member of some discords here and there, posting the stuff you see in the OP and stuff. According to the people that talked to him in VC and interacted with him in the discord in the OP, his real name was Bill (short for william) and he was 21 (this was confirmed by multiple members of the discord)
So Sephiroth, according to what we know, was unstable and erratic, posted a bunch of vile stuff, impersonated Plaz AND has the same name/age as the shooter. Coincidentally he also was last online before the shooting and hasn't logged back in.
That's it. That's the story I gathered over the course of today.