"Last Stand" is crucial for setting up the later events of Season 5 and 6, showing the Goa'uld as a crumbling empire being consumed by a stronger force (Anubis) while the Tok'ra face extinction.
The episode formally establishes Anubis as a devastating new threat who possesses superior technology, forcing the traditional System Lords into a defensive position. Critical Analysis 5x16_Stargate_SG-1
Daniel faces Osiris, who is inhabiting his former love interest, Sarah Gardner. He cannot bring himself to kill Sarah, even though her death would eliminate the Goa'uld symbiote Osiris. "Last Stand" is crucial for setting up the
Zipacna, acting under the new, mysterious System Lord Anubis, attacks the Tok'ra base, causing catastrophic losses. acting under the new
"I couldn't do it." (Referring to killing Sarah)