I prefer the multiplicative stacking. If the stack was additive instead of multiplicative Mage Stone + Lightning would outclass eternity as deckout prevention. Does sanctuary prevents stuff from being shuffled into your deck?
Sanctuary reads "Protection during foe's turn from hand and quanta control"
So no, because:
1) it is not active during your own turn.
2) It does not protect your deck (just your hand and quanta)
Hmmm... I suppose you could make it additive instead. But what is the point of going over 100%? In either case the card just gets shuffled to your deck...
More importantly, I don't like having the potential for 100% chance of silence recycling... or miracle... or sabbath... That's just asking for trouble. There needs to be an eventual sink off for those spells.