For just one mana, the Doctors mechanical mutt adds a nice layer of protection to all of your other legends, while also giving you the option to slip them through the enemy lines with his activated ability
It's cheap, it's flexible, and it replaces itself
While this is mostly a sideboard card since its other mode is very niche and rare to use, its very effective against decks that have the nasty tendency of flooding the board with small flying creature tokens
One thing to note is that Hazezons second ability considerably weakens its tokens, but you've got a few ways around this
To double the number of each kind of counter on a creature, put another counter on it for each counter it already has
We've seen experienced collectors sort through a stack of hundreds in minutes using these visual shortcuts