5-attack matters destruction deck for Expedition. Goes pretty well, can explosively close out a game with mightweaver. Has problems vs. control / removal heavy decks but hey that's midrange for you.
Strange Burglar wasn't in early versions of the deck but it ends up being a really good combo with Friendly Wisp, getting you even more card draw towards big threats and drawing into Mightweaver or Curtain Call. The self-damage and the non-bo interaction with Mightweaver makes it risky to keep drawing cards but the market Spiritweaver or one of the Curtain Calls can restore your health pretty easily. Furthermore the extra damage to your board on summon is another way to give your Dawnwalkers 5 attack, turning them into double damage overwhelm units if Mightweaver's on the board.
Getting the 4 time and 2 shadow is more important than getting the 2 fire, so don't worry about it unless Siege Train is literally one of the only playables in your hand. Getting at least one fire is pretty much always manageable with the plunder effects and Destruction Chant.
Oh, and Towering Arachnid is literally only in the market to trigger Friendly Wisp. You can play wisp on turn 2 and then market out the Arachnid on turn 3, choosing the wisp as a sacrifice and still getting the 2 cards off the wisp's effect. Otherwise it's not really worth grabbing.