doctorhydrogen

I'd think Guttersnipe, Talrand, and Young Pyro would be pretty useful here.

Wheel of Sun and Moon. Put those legends that get killed back into your library to fetch them again.

Do or Die is a pretty efficient force-people-to-saccrifice-stuff card. Yeah, there are times it doesn't do much good when they only have one creature out, but it's also a great way to wipe out 2-3 creatures in a single blow for two mana if someone gets out of hand. Only about a quarter to pick one up, too.

Minion Reflector is a relatively cheap ways to get reusable sacrifice fodder. Mimic Vat, too, though it's two bucks and not thirty cents like Minon Reflector.

Strionic Resonator is under a dollar, and you can use it to duplicate Grimgrin's ability to destroy a creature when attacking, meaning you can kill two per turn and gain two counters.

Yeah, I'd say Dust Elemental and maybe either Gideon Jura or Thalia. The problem with Thalia is that she hurts 1/3 of your own spells, and you may well run into lower creature (or creatureless) decks she won't hurt at all so she'll wind up helping other people. She's a great card to build a low-count deck around or in non-EDH formats, but I've never really had good luck with her as a one-of-the-99 in EDH.

I'd also consider swapping out Pacifism with either Arrest or Faith's Fetters. Arrest costs one more mana but it also prevents a creature from using abilities. There are plenty of creatures in EDH you want to not only keep from attacking but keep from doing annoying stuff, too, especially commanders. Faith's Fetters costs two more, but it prevents abilities and can be used on non-creatures as well.

Nevinyrall's Disk is a great card in colors that aren't white, but in white there are so many options I kind of hate to use a board wipe that I can't use immediately and that everyone has a turn to prepare for. Unless you specifically like to play it as something that sits there threatening people (which makes sense in some decks) I'd prefer to be able to wipe the board with nobody seeing it coming. Maybe Austere Command or Fated Retribution if you want an instant speed option? I've fallen in love with Fated Ret lately because usually with a wipe you use up half your mana casting it. With Fated Ret you can wait until the end of the player before you finishes his turn, wipe the board, then have a full mana base to start rebuilding.

Nykthos, Shrine to Nyx would probably love all those black mana symbols.

Nykthos, Shrine to Nyx would love all those white mana symbols.

Both Crackdown and Mass Calcify seem like they'd be useful in mono-white.

Snow-Covered Plains but no Extraplanar Lens?

Nykthos, Shrine to Nyx would love all those white mana symbols.

Both Crackdown and Mass Calcify seem like they'd be useful in mono-white.

Leyline of Sanctity has the same mana cost as Ivory Mask with the added bonus of being free to play if you happen to draw it. I personally probably wouldn't shell out the ten bucks to upgrade just for that, but if you happen to have one lying around I'd run it over Mask.

Homeward Path has become one of those auto-include lands for me in EDH. Not sure if you're in that boat yet, but I run into a lot of decks that try and steal stuff.

Thrumming Stone isn't cheap, but it would still keep you under 20, and it can easily chain out a dozen Apostles in a turn.

I'm running a Sigarda Enchantress deck with a heavy indestructible sub-theme that started out as a hexproof/shroud deck really similar to this. It was my experience that by and large having your creatures be untargetable wasn't really relevant (aside from beaters like Sigarda). After all, who is going to target Sacred Wolf or Gladecover Scout, anyway? Still, good luck with it. Maybe your experience will be different than mine.

That said, the one big issue with Sigarda (and Selesnya in general) is card draw. Both the shroud version and the enchantress version of my deck lived and died by card draw. I think you're going to find yourself in the same position. You are going to need ways to refill your hand, whether it's Mind's Eye or a Sylvan Library/Abundance combo.

Revoke Existence and Path to Exile > Naturalize and Artisan's Sorrow. With all the Theros gods and Darksteel crap in EDH you wanna exile artifacts and enchantments when possible, not just destroy. Fade Into Antiquity fits the bill, too, as does Deglamer.

Regrowth > Revive. Same CMC but Regrowth gets anything.

Good luck!

Good point. Stuff like Dauthi Embrace would, too, and you can do it multiple times per turn.

Viridian Longbow would combo nicely with your commander

I'd think all those black mana symbols would want a Nykthos, Shrine to Nyx.

Eldrazi Conscription is a monster in Bruna.

Traumatize with Bruna in play almost always results in a win.

Stuff like Launch, Glistening Oil, or Spirit Loop would give you an enchantment you could sacc repeatedly. Ophiomancer would make you a token to sacc every turn after you sacced one.

Grave Pact would make it so every time you sacced a creature using Ertai it also made everyone else sacrifice something.

I would also have a hell of a time not running either Stranglehold or Aven Mindcensor (or both). I see a metric shit-tonne of fetches and tutors though, and that may not apply to you. But for me, nothing makes me happier than dropping a turn three Mindcensor or turn four Stranglehold and watching the guy with 600 dollars in fetches in his deck stand there unable to use them or watch the guy who has stacked eight tutors be stuck with dead cards.

Gratuitous Violence turns those double-strikes into doubled double strikes.

Unfortunately in Mono-red the only real options to deal with enchantments would be Chaos Warp and maybe something like Spine of Ish-sha.

If anything I'd try to find a few more ways to do it, and maybe some haste enablers, too. With haste in play and the ability to tap Krenko 2, 3, even four times a turn you can end a person pretty fast.

Other untappers- Hematite Talisman, Jandor's Saddlebags, Thousand-Year Elixir.

Isn't Obelist of Esper worse than Coalition Relic, Chromatic Lantern, Darksteel Ingot or even Astral Cornucopia?