Have you thought about adding
Rhystic Study,
Phyrexian Arena, or
Necropotence for card draw?
Coastal Piracy helps as well but it needs combat damage, which should not be a problems with unblockable mechanics.
Whispersilk Cloak,
Key to the City are artifacts that help your creatures to be unblockable.
Altar of the Brood will put cards in your opponents graveyards and help mill and
Jace's Phantasm.
I'm not sure I like the extra turn... your creatures don't hit that hard and I don't see any infinite combos.
You are a very susceptible to board wipes and only have about 5 counter-spells.
Teferi's Veil makes your combat damage creatures phase out at end of combat and trigger more ETB effects.
Thopter Spy Network with
Darksteel Ingot will almost guarantee you will have a 1/1 thopter ETB every turn, plus it draws you a card on combat damage by a creature.
Just some ideas to bounce off of you.