For the most part I like it. The one glaring issue I see here is the land count. 21 lands is not enough for a deck that wants to get to 6 mana by turn 6. It's also not enough for snapcaster decks in general since you'll need to have plenty of mana to cast the snap and whatever you give flashback to in addition to other spells if necessary.
My recommendation would be to drop down to 3
Forbidden Alchemy and completely remove the
Conjurer's Closets. Then add 3 more lands.
From a fine-tuning perspective I might drop down to 3
Sun Titans and 3
Geist of Saint Trafts in favor of a 3rd
Phantasmal Image and a fourth
Mana Leak.
4 Geists is a little much since they are legendary. 4 Titans is a little much since they cost 6 and you really don't need to see more than the first one; you just have to keep them alive. Phantasmal Image has so many uses that I might even try to run 4 of them but 3 is a good start; plus, they interact so well with sun titan in the late game that there's nothing wrong with seeing tons of them. Lastly, your best turn 2 play is mana leak and you probably want to make sure you have one in your opening hand; running 4 will make this much more likely.