MTG Salvation

The first main combo is to get infinite attacks with Lightning Runner.
If you have Aetherwind Basker with Lightning Runner and at least 4 other creatures, then you can get the EEEEEEEE required to pay for the additional attacks.
Longtusk Cub and Aethergeode Miner can get you extra energy on the attacks, to reduce this number.

Empyreal Voyager with 6 power will also be able to generate the required EEEEEEEE for infinite attacks.
There are 5 cards that can get it to a 6 power: Huatli, Radiant Champion, Invigorated Rampage, Hadana's Climb, Verdurous Gearhulk, Engineered Might.

There is also a creature token theme. This is in part due to Aetherwind Basker, but also lends itself nicely to Whirler Virtuoso.

Each time a creature comes into play Aetherstorm Roc and Decoction Module gives us E. If you have both these in play along with Panharmonicon you can get infinite energy with Aethergeode Miner or Whirler Virtuoso.
You can spend EE on Aethergeode Miner, and it will return and give you EEEE.
You can get infinite 1/1's and energy with Whirler Virtuoso. Spend EEE and the creature coming into play will get you EEEE.

There are a few cards which allow you to copy either a creature or an artifact. This means that you will only need 3 of the combo cards, rather than needing 4. These are Mirage Mirror, Saheeli Rai, Saheeli's Artistry.

There are some other payoff cards for energy with draw in, Glint-Sleeve Siphoner, Shielded Aether Thief.

With a number of token creature generators, Fabrication Module helps the going wide strategy to also go large. You can get a lot of value off this card and get huge creatures. Another card to help with Empyreal Voyager.

Huatli, Radiant Champion and Tishana, Voice of Thunder can draw you a lot of cards with creature tokens.

Path of Discovery will allow you to filter through your deck quickly and give all your creatures a potential +1/+1.

Attack!
When it comes to the combo attack turn with Lightning Runner you want to be able to attack all opponents without it and potentially some of your other creatures from getting blocked and killed. So a number of cards can give evasion and others give them protection.
You can use Pia Nalaar and Huatli, Warrior Poet to make the biggest creatures on the board not block.
Driven // Despair and Open into Wonder can be used to draw cards with creature tokens, as well as being used for evasion during your Lightning Runner combo turn.
Heroic Intervention also allows you to attack with impunity.

Both modes on Engineered Might are useful for the deck as it can get you the power for Empyreal Voyager, as well as be used for a huge hit with your creature tokens.

Journey to Eternity allows you to get back your combo creatures with Atzal, Cave of Eternity if they have been removed from play, or milled. It also fixes mana, which is a factor in a 5 color deck.

Vraska, Scheming Gorgon is a card that I've been looking to put into a deck, as it has a straight up win condition. If you have this card, then you can take on the role of defending her until you ultimate, rather than being offensive. Plenty of creature tokens to throw under the bus to protect her. With the unblockable cards you can setup a turn where you can just alpha strike and kill each opponent.

Cascading Cataracts with Jodah, Archmage Eternal allows you to cast any card in your deck. Fixes colors as well as get some mana cost reductions with a few cards.

Hashep Oasis can be used to get Empyreal Voyager almost up to the combo threshold.