My favourite deck archetype is big butts - decks that use certain cards to allow creature with low power and high toughness (big butts) to do combat damage with their toughness, instead of their power. The advantage to doing this is you turen one mana 0/4 and 0/5 creatures into 4/4 and 5/5. Plus, I love to use Tower Defense to give his entire team 0/5 until end of turn. Tower Defense is only used when the creatures can attack with their toughness, turning an 0/5 ostensibly into a 10/10.

In Modern, this deck was originally Abzan (White-Green-Black), before Blue was added to make it four-colour. In Standard, since the advent of Arcades, the Strategist in M19, I have mainly used Bant (Green-White-Blue) or a two-colour variation with those colours.
Something we have never done before is add Red to the mix. Until now.

With the arrival of M21, one card jumped out at me as being an interesting addition to the deck. Subira, Tulzidi Caravanner allows you to spend one mana to permit a target creature with power two or less (which covers all of the big butts creatures) to attack unblocked.

The second ability of Subira allows you to discard your hand for two and a red in exchange for drawing a card for each creature with power two or less that subsequently does combat damage to a player until end of turn.

Now, Subira's not a huge payoff but it's a little extra for that deck. Allowing one or more creatures to be unblocked is huge for the deck and is the one thing that has been missing since Tetsuko Umezawa, Fugitive rotated out of Standard last year.

The red also allows us to put some red board wipes in the wishboard to get with Fae of Wishes. Thanks to the suggestion of one our viewers, we put three copies of Solar Blaze in the sideboard. As well, we threw in Scorching Dragonfire because the exile effect is nice.

Besides Subira and the two red spells in the sideboard, the deck is mainly intact from what we have been using in Standard over the past couple months, including in a couple of MagicFest Online events. You can see the deck in action here: https://youtu.be/Q3c-ZjmWfW8. We did take out the Lead the Stampede, the Yoked Ox and a copy of Tower Defense to make way for Subira and a couple of additional lands to smooth out the mana base somewhat, going to 24 lands from 22.

Other than We are still testing this deck but it has a lot of potential to get in those explosive hits for which the big butts decks are known. And since the two main enablers, Huatli and High Alert, are rotating out of Standard this fall, we might as well make the most of it. Now, the mana base is a bit questionable but Gilded Goose helps with the fixing. Check it out, give it a try and let us know what you think.