Getting past the bloody spider.

[DeepSoul]

I noticed you don't need poison resistance because the Spider attacks with physical and magic damage. The dark cloud he casts is magic damage. How do I know? He cast it on my Black Dragon and it only received around 80 damage. Black Dragons have 0% poison resistance 80% magic resistance. So the snakes are pretty pointless since their lunge attack still get retaliated by the boss. They also go down very fast because of their low defense. I started with 72 and at the end (before I gave up) I had only 14 left. I would recommend something stronger or a ranged unit instead. Units that can summon other units, for example engineers, is also a good idea because they can help tank the ever growing swarm of spiders.