lets destroy the sun

[Rubik]

It's been adressed and discarded on account of it only covers a couple miles of area on the surface of the planet and is an epic spell.

Yeah. We can do better with non-epic spells, which tend to be more powerful than what's already written for epic spells, assuming intelligent use and/or metamagic.

Also, it's postulated in some sources, such as the Manual of the Planes, that the sun in some campaign worlds is merely a gate to the positive energy plane (PEP).

It should be easy enough to close via Disjunction, or possibly with a Dimensional Anchor or Dimension Lock.