The Suswood mod will add some pretty interesting stuff to your game.

So far it doesn't add much: 1 new biome, mobs, and unique resources.

Let's sort everything out in order:

Spider forest Biome:

(sorry, I can't attach screenshots:( ...) 

In this biome you will find a new type of tree - Cobweb Tree.

The peculiarity of this biome is that only spiders an their new species, the Bighead Spider, spawn here. He has more HP and deals more damage.

Spider cocoons can also be found in this biome. Breaking them will drop experience and some loot. There's also a chance that a spider will crawl out of the cocoon.

A rare structure called an Arachnid Cave can be found in this biome. It contains a cocoon hanging from a web. If you break it, a boss, the Arachnid, will appear. It has 220 HP and deals damage with high knockback. It can summon enemies. It can drop either an Arachnid Eye or an Arachnid Fang.

The eye can be used to craft a spider amulet that grants buffs when held in the left hand. The amulet itself is crafted from the eye, iron, and mithril. Mithril is a new ore, blocks of which are rarely found deep in caves.

The fang can be crafted into a fang dagger. It deals 6.5 damage and has a very fast recharge. Right-clicking it will throw a poison potion in the direction you're facing, after which the ability will recharge.

More new content will be added in the near future. Thank you for your attention.