I love
Spider Rider, and it made me want to play
Arach, Razorshaper again. That's the backstory behind the terrible pun that is this deck's name.
The concept of the deck is simple. Both of these cards let you flood the board with Deadly dorks that clog up your opponent's play, and the more you buff them with spells and recur previous copies from the void, the better. All other choices are for added value around that concept.
Centipede Keeper is just a great 1-drop in a mono-Shadow-type build (you technically only need 1 Justice influence, to play
Against the Odds), with late game value.
Glen Pathcutter buffs Arach.
Acantha Ascending plays even more board-clogging dorks, while getting damage in the air and even some removal. The parenthetically-mentioned
Against the Odds is both a battle trick
and recursion. I love the design of this card, you can use it for a good trade or as a half-save against removal.
Besides our dorks, most of our removal is in the market, although
Final Push can be used that way in a pinch. As the extremely fair and balanced Hooru Kira has demonstrated,
Shadow Etchings counts for Renown and "play a spell on" effects. In a similar vein, so does
A Life For A Life, so you can get some terrific value from sacrificing Rider or using it for market access. Otherwise, you can sac something you're going to lose anyway from Push.
Makkar's Quiver gives a bit of interaction, and is really practically mandatory when playing Arach, since it buffs him and his dorks (same goes for Rider's spiders). I went with
Dark Return since it gives a buff, but it probably also makes sense to do
Sinister Rumors if you want interaction options. Rounding out the maindeck, with so many expendable dorks,
Tasbu, the Forbidden just prints card advantage. Getting your board wiped has a better chance of killing you from his damage then it does of setting you back on development. He also turns spent
Moldermuck clones into draws.
As far as the actual market goes, I just wanted the best stuff I could put in. I pull
Auric Interrogator first almost every time, with the rest as needed. Remember that playing
Pale Rider's Timepiece triggers Renown, because I certainly never do.