Oreskos Explorer is similar to Boreas Charger if you need more land search, except its ability is activated as soon as Oreskos enters the field.

Land Tax is another good land search, and can be out turn 1 is you have it in hand/first draw. If you really need more mana, Smothering Tithe is really nice and can help you leave lands open for extra available mana.

Single Combat is a fun new boardwipe and can help prevent opponents from rebuilding for an extra turn.

I see you have Smothering and land tax, I must be blind, sorry XD

Gift of Estates is another land search you don’t have listed.

Aww, bummer. I thought I would be the first one to make a Tomik, Distinguished Advokist EDH deck on Tappedout, and I had just uploaded my own. I didn't think of using Tomik as a death and taxes commander instead taking a different approach, but your list looks pretty solid.

I'd recommend Aura of Silence as that can really gunk up your opponent's ability to spam mana-rocks and other non-land mana-accelerators. I also find it works as a good deterrent when it comes to keeping your opponents from playing their best non-creature spells as you can always crack it on them before they can get any use out of it. For me cards like that and Seal of Cleansing have kept multiple opponents from making big plays even when I've only had one out which is pretty powerful what influence it can exert on the board.

If you have plans to run more artifacts in your deck Dispatch is another good card to keep around in your maybeboard as another Path-effect never really hurt anyone.

While I don't think white is the greatest when it comes to messing with other people's manabases you could totally run Quicksilver Fountain just to mess with all of your opponents. The fountain however can end up hurting your own manabase, but there's an easy fix to that if you also run Unstable Frontier . Basically you let a flood counter get placed on an unimportant land you control, and on your next turn's upkeep you tap the frontier to make that same flood counter land a Plains until end of turn. That means you can always put flood counters on the same land without any consequence because that land will no longer be an Island by the time the trigger resolves. Bonus fact, if a player removes the fountain the flood counters will not come off, and the lands stay as Islands which is pretty evil as you can remove the fountain yourself to permanently ruin everyone else's manabase.

Lastly Expedition Map might serve you well here. Being able to grab any land can be seriously helpful whether it's Dust Bowl , Emeria, The Sky Ruin , or Kor Haven . (As well as the Unstable Frontier I mentioned earlier.)

I hope that helps and good luck on the deck!

Thanks for the suggestions! I have had an in again off again relationship with Aura of Silence honestly. However I never considered the fountain as they get to choose what gets the flood counters. I forgot about dispatch frankly. I should put it in!

I forgot to mention Arid Mesa , Flooded Strand , Marsh Flats & Windswept Heath can be pretty useful to include. While at first they may not seem to do much, they make an incredibly strong synergy with Crucible of Worlds as you'll always be guaranteed to hit your next land drop that way by continually being able to pull them out of your graveyard. (Until you run out of basic Snow-Covered Plains of course.) Buying fetch-lands for such a minimal improvement might not be worth it, but if you have spares they really make a good synergy!

Speaking of snow-lands, Sunstone is a really good panic-button if one of your opponent plans to deal lethal out of nowhere. Being able to deny someone a combat step on demand is pretty strong, especially if you have a Crucible of Worlds to fuel it.