Aflatoxin is one of the key cards for setting up, as you need to be able to use Dry Spell when there is a field of Malignant Cells to summon the Ice Dragons.
Chimer is to help get past any pesky shields at the end, like with most decks. Not always necessary.
Enchant Artifact is to protect your Unstable Gasses, but that is set to change, such as using them as protection against Jezebel or any PC heavy deck as you need the Hourglasses to draw.
Rage Potion is to help kill bulky creatures to get the Malignant Cells up and running. Also, if you save one for the ending combo, you can actually get an additional 30 damage, which you may need if you lose one or two of your UGs.
Ice Dragon will be your main hitter as it's the strongest cost-to-attack
creature available.
Dry Spell will be necessary in generating the
for all of your Ice Dragons.
Sanctuary offers light healing and saves against the dreadful Black Holes.
Unstable Gas will be making up for the damage the Dragons will not do and are great as only 4 False Gods can reflect.
Sky Blitz is obvious since this is a Dragon based OTK.
Golden Hourglass and
Sundial are key in massive draw power as well as stalling the damage you'll be taking.
Cloak protects your fragile Permanents and at least force the use of a card on it rather than on the Permanent.
Parallel Universe and
Fractal will be for your mass source of Dragons.