I've been playing it in mine and if you combine it with Lyra, it's incredibly powerful, so yes absolutely it can fit in. If you're looking for a card to swap out, I would suggest the Glimmeroot. It occupies the same mana slot and Glimmer doesn't really help the end game much in fairness.
Dropping 5/5's also is incredibly potent against heroes that choose to armour up like Warrior and Control Druid. These can be tough otherwise to get the damage output to get through to lethal.
Can it fit in a razakus deck?
If you're looking for a card to swap out, I would suggest the Glimmeroot. It occupies the same mana slot and Glimmer doesn't really help the end game much in fairness.