"We've survived starvation, dwarf attacks, and heatstroke. Why should a little sandstorm bother us?"
Gush Banned
RIP Gush - you died for Delver's sins...
The Combo
Tireless Tribe allows you to discard a card to pump it +0/+4 - the idea is to discard 5 cards to make it a 1/21, then use Inside Out to switch its power/toughness to a 21/1 for a win. By using layers, we can cast Inside Out before discarding cards, as the effect lasts until the end of the turn and applies to anything that affects power/toughness.
Shadow Rift makes Tireless Tribe unblockable by giving it shadow (and replaces itself by drawing a card).
Whiteout for additional card advantage on the combo turn in a world without Gush (RIP, although Whiteout might actually be even better).
Card Advantage/Selection
Brainstorm, Ponder and Preordain dig through the deck to find what you need. Evolving Wilds and Ash Barrens provide shuffle effects for Brainstorm and fix mana at the same time.
Frantic Inventory gets more cards as the game goes later, hopefully overfilling our hand for the lethal turn.
Other Spells
Seeker of the Way chips in for damage (usually gaining life at the same time) and blocks like a champ. Seeker also acts as a perfect lightning rod to eat removal - he almost always needs to be removed on the spot, the lifelink just gets out of control.
Gigadrowse for tapping down opponents lands (for beating instant-speed removal/counters), blockers (to get Tribe through) or attackers (for stalling).
Circular Logic is usually just a straight counterspell that also pumps Tribe, Dispel counters instant removal or other counterspells.
Sideboard
Prismatic Strands for discarding to Tribe and still having a Flashback-able spell.
Hydroblast for defense against burn/other red creatures.
Piracy Charm does a lot - removal/discard/evasion, depending on what the situation calls for. It also protects Tribe a bit by giving it -1/+2 after casting Inside Out.
Echoing Truth for a bounce spell.
Journey to Nowhere for other removal.
Maybeboard
Delver of Secrets
for some chip damage (can usually always flip right away, makes winning with Tribe a little easier), swapped out for Seeker in the sideboard when life gain is needed over damage.
Standard Bearer eats a removal spell pointed at Tribe, also affects Infect/Bogles.
Squadron Hawk nets 3 cards in hand and is a non-Human for casting Of One Mind (which also nets one card per cast).
Tethmos High Priest for re-buying killed Tribes/Seekers.
Thought Scour mills away Brainstormed cards and also cantrips.
Deep Analysis as a one-of for more card advantage/discard fodder.
