(Spell Casting Ob 3^)
Three successes to successfully cast (change the shape of one small palm sized obeject) Extra successes can be used to increase the effect of the illusion (size, complexity) regardless, you cast and tax against the Ob 3, the caret (^) simply means that extra successes can make the spell even better, as opposed to a “flat” spell (no caret) that only has its listed effect.
Check out the Sorcery chapter for further information (499 - 521)
The Sorcerous would need to roll three successes to properly cast her spell, any extra successes could be used to improve upon the basic illusion (a convincing elephant would probably need at least three or four extra successes).
Regardless of the success or failure of the spell, she would test spell tax against Ob 3 (plus any applicable penalties), the breath and scope of the intended illusion has nothing to do with the spell tax as it is only accomplished by generating extra successes.
If the Sorcerous only received enough successes to cast the spell, she gets a palm sized elephant.
I’d, in the case of a plan which absolutely requires a life-size elephant to work, adjudicate Spell success based on Ob 3, including not punishing failure with DoF and potential garbled transmission. But as an intent and task, I’d treat the Ob ofor getting your intent as (probably 7 but that might be argued)
The Obstacle for advancement is a different matter, and I’d have to choose which one was relevant carefully.
Also, if the Intent does not involve a time limit, I would ask the players if their character is casting carefully or not as the assumption would be they are taking every conceivable advantage to accomplish their goal.
A 5D Sorcery can benefit by as much as a +5D bonus by multiplying their casting time by ten. In this case, that’s 560 actions (roughly five minutes)
That’s a very long time to be casting a spell unobserved.
If you want a good spell for advancement check out Low Speech (pg. 214). It’s a great utility spell for Sorcery advancement as the players can set the obstacle according to what he wants to talk to, anywhere from apes and simians ( Ob1 ) to insects (Ob8 ) and everything in between. All for a meager 8 Resource Points in Character Burning!
Mage Light (215) is another variable obstacle spell that allows the players to choose the spells intensity, and therefore, it’s obstacle.