Hi! Deck seems sweet with all the card draw and powerhouses. First thing I thought of was
Reliquary tower to prevent forced discard.
With all the basic Islands,
Vedalken Shackles would probably be great here! and
Shackles pairs really well with another card worth considering,
Proteus Staff. Since you're pretty creature light, and most of the creatures are giant, the Staff could cheat one in play pretty easily. And even if you just hit Muldrifter, at least you'll draw 2. Or just use it with your opponents shackled creatures
I hope you found this helpful! Good luck and Happy Hunting