It's probably mythic. While all non-common rarity symbols in the set have a lighter-colored center, the rares have the center be a light yellow (as compared to the usual gold color), while mythics have this dark orange color fade almost entirely to white. Here are a bunch of artifacts from the set for comparison.
I think it's more and more evident now that they mashed two Master sets ideas together to create this one. From EDH point of view (which is 2020), it replenishes key cards a lot quicker than one of the regular Master set from the past, so I'm ok with it.
Drat bought one a few months ago when working on the reaper king I guess I can get a second one for kozilek now
can’t tell if it’s rare or mythic due to blur
|| UW Jace, Vyn's Prodigy UW || UG Kenessos, Priest of Thassa (feat. Arixmethes) UG ||
Cards I still want to see created:
|| Olantin, Lost City || Pavios and Thanasis || Choryu ||
Shu Yun, the Silent Tempest WUR Voltron Control
Temmet, Vizier of Naktamun WU Unblockable Mirror Trickery
Ra's al Ghul (Sidar Kondo) and Face-Down Ninjas
Brudiclad, Token Engineer
Vaevictis (VV2) the Dire Lantern
Rona, Disciple of Gix
Tiana the Auror
Hallar
Ulrich the Politician
Zur the Rebel
Scorpion, Locust, Scarab, Egyptian Gods
O-Kagachi, Mathas, Mairsil
"Non-Tribal" Tribal Generals, Eggs
Not to mention, a good way to ensure people don't get all what they want by increasing the mythic size.
Shu Yun, the Silent Tempest WUR Voltron Control
Temmet, Vizier of Naktamun WU Unblockable Mirror Trickery
Ra's al Ghul (Sidar Kondo) and Face-Down Ninjas
Brudiclad, Token Engineer
Vaevictis (VV2) the Dire Lantern
Rona, Disciple of Gix
Tiana the Auror
Hallar
Ulrich the Politician
Zur the Rebel
Scorpion, Locust, Scarab, Egyptian Gods
O-Kagachi, Mathas, Mairsil
"Non-Tribal" Tribal Generals, Eggs