Bioshift is a great card! If someone focuses blocks on your biggest creature, or if you need an unexpected blocker, Bioshift is the way to go. It's an instant speed permanent buff that's as big as your biggest creature, so long as you've got the necessary +1/+1 counters out!
What's more, if you have a Corpsejack Menace, those counters get doubled at no extra charge... and if you have two, they get quadrupled.
As for the Unsummon, I have those in over more Simic Charms because I need a lot of mana to do a lot of stuff during one combat phase. Being able to grant my creatures hexproof until end of turn is important, but I'll also need that extra green mana to get a Corpsejack Menace out, then Bioshift my counters onto a
Vampire Nighthawk
and Unsummon their only flier for an unexpected lethal blow from a 2/3. Or sometimes with the Master Biomancers out, I can wait until the end of my opponent's turn to Bioshift counters from an Ambush Viper onto a Biomancer, Unsummon the snake, and then recast it with loads more +1/+1 counters.
That's the beauty of Bioshift: if there's even one creature your opponent can't or won't block, you can divert damage onto your opponent from their blockers through that one creature!
I threw every relevant dual land I had in here, but I still need shock lands and more Hinterland Harbors. I think this deck is really cool and exciting. I hope it's worth skipping my physics homework for.