Before Thrash became defined, refined and confined, there was room for interpretation. Thrash had to come from somewhere. I think this album was a major influence.
These guys were from Finland, but they easily could be mistaken for a band from the NWOBHM. I've seen them compared to Raven who were certainly early thrash.
The album has a bit of a cult following. Little known but highly revered. It's short at 27 minutes, but all you have to do is flip it back over to side one and get blown away again, which is exactly what I just did. Finally ripping the vinyl to digital after all these years.
Oz - Fire In The Brain
1984 Combat MX 8006
https://www.discogs.com/Oz-Fire-In-The-Brain/release/2491467