(3.11) Vadrik, Astral Archmage + Dragon's Approach (EDH / Commander)

Turn 3: Cast Vadrik, Astral Archmage. Thanks to one of Vadrik's abilities and his existing stats, 1/2, instants and sorceries cost {1} less.
Turn 4: Don't cast anything during your turn itself so that it becomes night, triggering Vadrik and getting one +1/+1 counter, increasing Vadrik's overall power and toughness to 2/3. Instants and sorceries now cost {2} less. (Alternatively, you can cast Standstill on your turn itself, so that your opponents won't cast anything hopefully and it will become night.)
On your opponents' turns, you have a bunch of instants that you can cast for {2} less, including many counterspells (7% of the deck) and card advantage spells (9% of the deck). If there isn't anything to counter, Occult Epiphany is probably the best option, because you can draw and discard a bunch of Dragon's Approaches, which comprise 30% of the deck. Borne Upon a Wind is also great, because it only will cost {u}, and then you can cast a bunch of Dragon's Approaches at instant-speed for only one {r} apiece.
Turn 5+: Cast as many Dragon's Approaches as you can, for only one {r} apiece. Once you have enough Dragon's Approaches in your graveyard, Dragon's Approach lets you tutor and play a dragon. Ancient Silver Dragon and Dragon Mage are great for card advantage and they'll keep the engine going. Tyrant's Familiar is great for removal and he has haste. Sprite Dragon is also an option, but it's nowhere near as good as the others.
Whenever possible, switch to day or night so that Vadrik gets a little bigger. Passing yourself without casting a spell is the most reliable way to switch to night, but you can also discourage your opponents from casting anything with the threat of a counterspell if you leave enough blue mana open. Since each Dragon's Approach only costs {r}, it should also be relatively easy to cast two on your turn and switch to day.