This is an interesting look at the concept of symbiosis, by creating a character class defined by the presence of a symbiote. In this interpretation, the symbiote confers combat advantage to its host through possibilities of morphing the host's body to generate, for example, claws or fangs (or for that matter, armour).
The development of this concept is good if marred by sloppy grammar, particularly abuse of apostrophes, and by calling the symbiote itself the 'urge' when that term would appear to be better applied to whatever it is that the symbiote wants out of the relationship. This idea, that the symbiote wants something specific, is well handled as a concept, with a rule mechanic to measure if it is getting enough of whatever it wants - neat!
There is plenty of scope to take symbiosis as an idea further - there are many different kinds of advantages that having a symbiote could confer, and it is not something that necessitates a complete character class - a wizard, say, with a symbiote that boosts his intelligence could be a formidable character... no matter that his symbiote is so curious that the poor wizard starts each day tired and red-eyed, because the symbiote was using the wizard's body to read magic tomes all night! The upside is that the wizard can access the knowledge, the downside is that he has not had sufficient rest to function well physically.
As a start in looking at this fascinating and unexplored area in fantasy gaming, this is a good one! Food for thought indeed.