Spiders -- Attack of the Lawn (Casual)

Spiders. Huge-ass spiders. And contagion engines.

This deck's done pretty well for me, I'm just looking to make it better. The whole cost is like ~$20 so I'd like to not spend a lot more.

Right now I've got a proliferate focus. Bond Beetle, Aquastrand and Blessings of Nature set up for the Engine. Arachnus spinner/web locks down problem creatures. Silklashes and Recluses form the anti-aggo wall, while Spinners/Sentinels/Archweavers swing away. Rancor helps out anything that's not an Archweaver.

Bioshift fills a special role--often times I'll swing with multiple things, the opponent will declare blockers, and before combat is calculated I'll shift counters to whatever they didn't block. I beat someone with a 26/26 Archweaver this way.

For mana, I've got two StH's and two Explores, which get the job done satisfactorily.

My biggest issue is a lack of removal. I'd like to keep it mono green, and not add too many non-spider/insect creatures. I also don't know what to put in my sideboard--is that where I should stick some Naturalizes?