I love unconventional tribal builds in casual because not only are they usually cheap but they present a challenging build. After some tweaking and test playing with my friends this was the best I could come up with in Tribal Spiders.
As standard for many golgari decks filling the graveyard is key. To do this while digging for lands and creatures we have grapple with the past and grisly Salvage. Great for making sure you get that extra land you need or a creature to build your board with.
Instead of straightforward removal I opted to go with drown in filth. This is not ideal by any means but will help to build the graveyard as you go. Your first one should kill any 1 or 2 toughness creatures and later ones will have a more profound effect for sure but very large threats will just have to be waded out.
Assault Formation is pretty important and you will want it out as early as possible to make your spiders a real threat in combat, but the main strategy is to win through Rotwidow pack, and ishkanah's abilities.
Nyx weaver will help you mill as well as give you opportunities to recover spells like Victimize, drown in filth, or assault Formation when needed.
Getting tokens with arasta, ishkanah and rotwidow pack is great but remember to wait till your opponents term before sinking that 5 mana because you may want to leave up that 3 mana for arachnogenesis. This will be a major play as far as removing creatures too large for drown in filth as well. Then your spider count is boosted for the next turn anyways.
Deadly recluse, obelisk spider, and penumbra spider help fill out the meat and potatoes of this deck. They provide deterrence, efficiency, and self replacing respectively and with assault Formation out make for some solid defences.
Use victimize on a penumbra spider, token, or if you're grabbing a different ishkanah, your origional one to fortify your board. And if you're up against a control deck and all else fails you still have svogthos, the restless tomb to fall back on.
I only run one copy of gnaw to the bone because by the time you get it, it should actually be worth using. And should you mill it you can still use it anyways to buy you time to bleed them with triggers.
This is by no means a great deck but it is decent and really fun once you figure out the nuances of strategy to keep building yourself up to drain them to nothing. Set the trap, tie them up, and leave but a husk of your enemies in the wake of... 8... Legged... Geeks...
