How's this for a monster suggestion?

Insect: They’re the most fragile of all monsters, possessing very very low amounts of HP and defense. The only reason most of them are able to survive is that their small size combined with their high speed and reflexes help them avoid attacks. Their small size also helps them at remaining unseen, making them good at hit and run tactics. When they transform they can gain the ability to raise their defense by developing an exoskeleton, create traps and be able to reach objects far away by being able to shoot web, spit poison, etc. 

Skills: 
Crawl I: Insects are able to move in walls and ceilings for a small amount of time.