Quote from Pokken »Sacred Mesa
If you play the epic enchantment search card, Sigil of the Empty Throne is pretty sick.
Quote from Cythare »Yes, you can get an extra turn. Ugin's Nexus doesn't stop extra turns from being created, it stops them from starting. If you can bounce, phase out, destroy, or otherwise get rid of the primary copy before your extra turn would start, it won't be able to step in and stop you.
That being said, note that Ugin's Nexus doesn't have any triggered abilities - it has two replacement effects - so 603.3d doesn't apply anyways. Nothing goes on the stack. When the token copy would be moved to your graveyard due to SBAs, it will replace its zone change to end up in exile and generate an extra turn, and player's can't do anything about this, since it all happens before a player would get priority. Now that your extra turn has been generated, you have until the end of the current turn to remove your other Nexus.
Quote from user_938036 »It doesn't say you can't generate effects that would cause an additional turn, it says if you would begin one skip it. So as long as you get rid of the nexus before your turn ends you'll get your extra one, though with that set up it would be 2 extra turns
It's probably easier to sack the original to legend rule as the copy won't stick around to make you skip a turn