The combos explained:

Red Line
This is the main combo line. Tatyova, Benthic Druid + Ghostly Flicker + High Tide + Mystic Sanctuary gives you everything you need to go off: You cast High Tide, tap Island and Sanctuary for  and then cast Ghostly Flicker on Island and Sanctuary. The Sanctuary puts back Ghostly Flicker on top of your library from where Tatyova draws it, then Tatyova draws a 2nd card. This loop generated 2 life,  and 1 draw. Now you proceed to draw your library until you find an Archaeomancer and start looping High Tide over and over again to go truly infinite, by casting Ghostly Flicker on Sanctuary + Archaeomancer. Then you draw until you find Compulsive Research, which you then loop on your opponents the same way you've been looping High Tide. If Compulsive Research somehow got exiled, you can still Capsize your opponent's entire boards (lands inclusively). From there on just kill through (commander) combat damage and/or protect yourself from decking by Capsizing your Sanctuary each of your turns and put a spell back on top to draw for turn, while you combo in each of your opponents turns again to keep them locked out of the game. Alternatively you could also choose to play Deep Analysis in your deck as a second Compulsive Research if that floats your boat. Instead of High Tide, you could also use Peregrine Drake and just go truly infinite without the need of an Archaeomancer besides Mystic Sanctuary. Or, while we're at it, just cast Ghostly Flicker on Archaeomancer + Peregrine Drake to go truly infinite without the need of both, Tatyova as well as Mystic Sanctuary. That one I marked as the green line and is just to show that you don't necessarely need Mystic Sanctuary to go off with this deck. The next combo line, the black one, will show that you dont necessarely need Ghostly Flicker either. Last but not least, Tatyova + Ghostly Flicker + Mystic Sanctuary can go infinite with Cloud of Faeries + Simic Growth Chamber as your mana acceleration instead of High Tide or Peregrine Drake.

Black Line
This is an alternative combo line that takes a lot of pressure away from Ghostly Flicker. Including Tidal Bore in the deck has as low opportunity costs as you could think of and allows quite an effective alternative combo. Tatyova, Benthic Druid + Mystic Sanctuary + Sakura-Tribe Scout + Tidal Bore gives you infinite blue mana and infinite life, too: Tap Sanctuary for blue, activate Sakura-Tribe Scout, keep priority, cast Tidal Bore on Sakura-Tribe Scout by returning Sanctuary to your hand, let Tidal Bore resolve which untaps Sakura-Tribe Scout, then let its activated ability resolve which lets you put Sanctuary into play. Order your Sanctuary and your Tatyova trigger so that Sanctuary's resolves first, put Tidal Bore back on top of your library and immediately draw it with your Tatyova Trigger. This loop gained you one blue mana and one life. There is 2 very important details about this combo. First of all, it doesnt draw you cards, so you have to find a way to sink your mana into draws. Most of the times this will be Whispers of the Muse for this combo, but there is more. Of course, if you just happen to find a Ghostly Flicker on the way, that'll do as well. But there is also some ways with your bounce spells: If you somehow have access to an Archaeomancer (or Mnemonic Wall or Salvager of Secrets or Scrivener) plus either Into the Roil or Blink of an Eye, you can cast your bounce spell on your Archaeomancer to draw a card and then replay your Archaeomancer to get back your bounce spell. This loop draws you as many cards as you want when you have infinite mana. The same goes for an Archaeomancer + Capsize if you just have any carddraw spell laying around: You can always Capsize your Archaeomancer to get back a Preordain for instance and with that draw your library as well. The second detail about this combo is that at the end of it, with your last Sanctuary drop, you can always get back an instant or sorcery, which often times allows you to just recycle that Merchant Scroll or Muddle the Mixture or Dizzy Spell (or the Whispers of the Muse itself) from your graveyard. And all of these tutors will actually find you a mana sink to draw your library with. So the downside of needing another combo piece to draw your library with, actually doesnt really exist most of the times, because you're almost always already covered in that regard.

Credit to MtG_Crash https://www.moxfield.com/decks/xtsZ51FFS0SptMlsZ1BweA/primer