|James MacKenzie RPG Superstar 2008 Top 16 aka Sir_Wulf|
My players quickly guessed what the toy was for, so I had it make squeaking noises when squeezed. Some of the players decided to kill the basilisk anyway.
When I ran the finale, the party made their stand in the same chamber as the Golden Guardian. I added three Aspis minions to each of the invading parties: These became the Guardian's opponents. Their attacks targeted the guardian and he generally tore one of them apart each round. When PCs attacked one of these "supernumeraries", a different villian took his place as the Guardian's dance partner.
This allowed the party to see the Guardian in action as an ally without meaningfully altering the difficulty of the fight. I also had the big bad throw one spear shot at the guardian and "crit" for a crapton of damage: This emphasized his badassitude and worried the party that he was going to take their ally out.