Negative Zero said:
i agree with Storminator. if you fail your save, then you believe the illusion fully. if it's of fire or a torch, then you'd see what you expect to see, not necessarily what's actually there. and yes the fire would feel hot to you, because you mind would tell you that it is.
Those would both be house rules.
Figments cannot shed light, even illusory light. No observer can be "fooled" into seeing in the dark (or thinking he can see in the dark), because that is simply not within the capability of the spell. If you take a figment of a torch into a dark room, you will find yourself in unilluminated darkness, regardless of whether you made your Will save.
To put it another way: a figment is not a mind-affecting spell. Even if you expect the figment torch to light your way, you'll quickly realize that it doesn't. (Say you enter a dark room IRL, carrying a flashlight with dead batteries. You expect it to light up when you flick the switch, but it fails to do so. Do you suddenly hallucinate the appearance of a beam of light? No, you realize that it's still dark, and therefore something is wrong.)
As for heat, read the spell description.
Silent Image explicitly cannot simulate temperature or texture. The
Silent Image of a bonfire would not shed any heat at all, even for a character who fails his Will save, because that is simply not within the capability of the spell. (If you want to simulate thermal effects, you need
Major Image-- a more powerful magic.)