Intro
I like many others had the fantasy of making an deck:Assault Formation deck when Origins came out. They utilize creatures that need not have any attack but large toughness instead. These are harder to remove because of that and also pack one hell of a punch when combined with Assault Formation. Also the fact that they have tiny mana costs allowed one drop the equivalent of a 4/4 using one mana.
There were two main issues with these decks:
1.) They all REQUIRE it to be on the field, and if its removed there's not much they can do. It is so easily removed and there aren't too many ways to protect it.
2.) The mana cost to have your creatures with defender attack limited its usage and removed the benefit from having such a low mana cost.
These were responded to by having decks that attempted to attack worth 20 damage on 3rd or 4th turn. This was so easily responded to with chump blockers that it simply wasn't viable in a competitive setting.
The latest expansion seemed to breathe new life into the concept centering a deck around Assault Formation not only because of the board wipes that are no longer Standard, but with the introduction of Tide Drifter
Strategy
Unlike previous Assault Formation decks I've seen, this one does not try to win on the first few turns. It doesn't have much chance in late game against most decks, but it can hit hard enough to deal 20+ damage in a single turn at midgame. The hope is to sit on Assault Formation and play it on the turn I'm ready to swing hard. The low number of creatures with defender frees up mana sources and I can Dispel away attempts to remove Assault Formation before damage is decided. The mid-game target for ending the game means you aren't dead in the water if you don't draw Assault Formation Your walls can keep you alive until you do.
Card Choices
Tide Drifter Two reasons why I think it is useful for an Assault Formation deck.
It has a high toughness but doesn't have defender, removing the need to pay to attack
It lends toughness boost to colorless creatures, increasing the likelihood of being able to deal 20 damage with only 2 or 3 creatures getting through.
Benthic Infiltrator Not the best toughness for the cost, but its unblockable. I wont need to give it trample to deal with chump blockers and it makes a convenient target for dumping all of my toughness boosters into in hopes in ending the game on a particular turn.
Guardians of Meletis A colorless wall that can benefit from Tide Drifter I'm very much open to replacing this guy with a better option. This will be one of my first choices for switching out for a sideboard card, but I'd still rather have it on my mainboard than Auramancer for game 1.
Yoked Ox Doesn't benefit from Tide Drifter but can still swing for 4 and only drops for 1 mana. I can Press the Advantage with two of these guys for 12 Trample damage. That could be a game winning swing if I have free green mana and a Shape the Sands. Benthic Infiltrator isn't going to be sitting idly by if hes out. Even with no Assault Formation he'll be chipping away at the opponent. Yoked Ox doesn't combo with everything in this Deck, so this little guy wont be the highest priority for removal. Slipping through the cracks with 12 ain't a bad thing to throw in.
Brave the Sands Having a deck filled with toughness monsters allows me pretty good blocking capability. I cant utilize that if they're all tapped from attacking. Hence the Cheap Vigilance of this card. One of the weaknessess of this deck is simply being outnumbered by smaller creatures or tokens, and the ability to block two creatures will help mitigate that as well.
Glaring Aegis Is a nice cheap enchant creature that adds 3 to the swing of a creature and removes a potential blocker at the same time
Press the Advantage Has a pretty steep mana cost for this deck, because keep in mind: if the opponent is sitting on an Erase they'll wait until after blockers are declared to take out Assault Formation. I'll need to leave mana open for a Dispel before I go for this. Assuming I have enough mana, this can be a wincon. I love that its an instant, so I can wait until after blockars are declared before I decide who gets trample
Starfield of NyxIs a late game attempt to get Assault Formation back. If the game goes long enough to pay the cost, i'll welcome this draw. If I get this in an opening draw, it'll probably be a mulligan. I swap this for pretty much anything on the sideboard if it doesn't look like the opponent has much enchantment removal.
The lands are focused on having many fetch lands, so I have a high probability of drawing lands early game, but less so late game, so I can draw something more useful. I'm wincing at the lack of ability to choose between Forest or Island in standard right now, so they're off balance, but playtesting still seems to work out just fine.
This deck obviously wont compete with Tier 1 decks, so it probably isn't worth the money for some of these lands. The low mana cost of most of the cards means that this deck will work out fine with some cheaper lands that come into play tapped. I would strongly consider Evolving Wilds simply to gain the ability of fetch lands to give you a a good chance of drawing lands early game, but less so later in game.
