deck is built to take advantage of immortal throne, grosse poltergeist, scavenging fiend, and buried treasure primarily

in order to make throne good, we need to run a really weird curve. ideally, the turn we play throne, we have an untapped seer, so we can instantly tap it to play a land, drawing a card, then follow it up with a 1 drop, drawing another card.

to that end, i figured mix ignis was a good way to make that happen, along with pit vipers and the gnomes. ignis also helps cast big stuff, which is something the deck has issues with, and helps us with cool but expensive sequences, such as seasoned sellsword, pitch undertaker engine -> scavenging fiend. mix makes that a 3 mana endeavor, which is outstanding. vipers and gnomes help us recover buried treasures and resurface buried or earthquake'd artifacts such as spear of destiny or payload trebuchet, along with letting us safely tuck angels eggs under our sites, and devil's eggs under our opponents.

2 drops are pretty easy, we have sellsword which synergises with scavenging fiend and battlefield, we have land surveyor, which helps us play sites consistently and helps man our trebuchets. usually, if our throne turn is as we desire with throne -> site -> 1 drop, our opponents will play a 2 drop during their turn to try and capitalize on that sweet, sweet card draw, so we often won't even get a chance to play a 2 drop, but its still nice to have some to help is fill curve neatly and to meet that requirement if our opponent makes us level up the throne ourselves.

3 drops are also pretty easy, as not only are two of our focal cards three drops (poltergeist and buried treasure), but the eggs are also three drops, in addition to root spider, a good way to slow down our opponents, bait out floods, and to carry our treasures to the surface. spider is also good for protecting poltergeist, as even if poltergeist is disabled, the artifacts it animated remain so. the eggs synergize with buried treasure, serving as further justification for such a large package of burrow minions. buried treasure itself also finds support in secret tunnel. some well-placed-and-planned secret tunnels can make it trivially easy for a buried treasure placed anywhere to be surfaced asap.

4 drops include infiltrates and scavenging fiends. i've ran a single copy of rolling boulder in the past to help with this, but 4 drops as a whole are pretty popular in multiplayer. lots of the best/most fun threats and answers can be found in the 4 drop slot, so often we can rely on our opponents for help here too. (examples of commonly found 4 drop threats and answers include thunderstorm, clamor of harpies, captain baldassare, ruler of thul, pudge butcher, skirmishers of mu, infiltrate, and chaos twister). another minor reason why we might not care about 4 drops much is because if we, on t5, go throne -> site -> 1 drop, we probably won't have another site in hand, and won't want to draw one next turn. thus, we're likely going to have 5 mana, and therefore are cleanly able to either play a 3 drop and a 2 drop (both of which can help level the throne the turn after it comes out), a 3 drop and a mix'd 4 drop, or a 5 drop (which may trigger the throne if our opponents are feeding us)

5 drops include spear of destiny, payload trebuchet, and poison nova. they tend to be enough, though they also tend to be awkward on curve. mix helps, but this is just our most awkward spot on the mana curve. however, you'll often find yourself using seer to help use artifacts such as payload trebuchet, or to recover thrown spears/lost eggs, which sometimes means you just won't play sites after your fifth for a couple turns. if the five drop you're playing is poison nova, this is especially true, as you'll often want to take a step outward to kill more minions with the spell.

6 drops are the worst spot on curve. there just aren't many options period, and most of them suck. purge juggernaut is terrible outside of a hyperfocused water shell (easily dies to attacks, can never attack back, only threatens in a cross shape), so i've stuck with flame wave and pendulum of peril. another benefit of the burrow minions is that they often can hide the turn that you plan on flame waving. (also mix casts flame wave wooo)

7 drops are simple, we've got major explosions, undertaker engine, and death dealer, two of which are castable by mix ignis. undertaker engine is a star performer in the deck, allowing us to easily recover lost buried artifacts that are unable to be carried (LIKE IMMORTAL THRONE), to swiftly kill a host of invaders, and to bring up burrow minions holding buried treasures, along with being the best target for scavenger fiend. i would run boneyard, but in multiplayer its hot ass, since it lets everyone bring back a minion. i would like to swap death dealer with wraetannis titan, since the titan accomplishes much of what the death dealer does without preventing our opponents from killing each other and without killing our burrowing utility minions, but the death dealer is castable off mix, and 7 mana is nearly impossible to get to in this deck.

you can swap poison nova to earthquake if you want, but i prefer it because its castable with mix ignis, it's more fun to have to move yourself to a good position to use it, and earthquake is just very strong and flexible. the deck isn't looking to play a super optimized gameplan. if all my multiplayer decks played all the cards that were good in multiplayer, we wouldn't really have games because everything would just die as soon as it came out, and nobody would get to do their synergy thing. pretty lame.