Just a quick question on how Improved Share Spells and Spell Sponge interact... how do you calculate the duration of those spells? Spell sponge doubles the duration on your familiar. Improved share spells forces you to divide the duration between you and your familiar. So, which math is done first?
In the example of a wizard casts a ten round spell it would normally, with Improved share spells, last 5 rounds each. However, the Spell sponge increases the duration on the familiar.
1) 5 rounds on the Wizard; 10 on the Familiar? Apply share spells first, then apply spell sponge.
2) 10 rounds on each? Wizard casts the spell on the familiar. Spell sponge kicks in and doubles the duration to 20; then it is divided amongst them according to Improved Share Spells.
3) 7 rounds on each? One would last 10, the other would last 20; so you average it to 15 and divide them.
I think I would go with reading 1. I'm playing the wizard in question and I think that reading 2 is a bit cheesy. Especially since I'll be employing a double-telekinesis tactic to push things into my pits.