This is already one of my favorite iterations of
the famous "punisher" abilities. If the Gearhulk
manages to hit play, your opponent has fewer
good options than with a lot of punishers. Its
combat stats make it hard to deal with, and
while it might look like an easy choice to never
let your opponent draw the cards, you have to
consider that a huge amount of damage coming
straight at you (depending on what exactly is in
their deck) might be worth a lot more than three
cards. For a lot of decks, having things in
their graveyard - having the right things in
their graveyard - is definitely worth a lot more
than three cards.
Out of the thus-reviewed Gearhulks, Combustible
Gearhulk may be the best one in combat. 6/6 with
first strike means it beats the other Gearhulks
we’ve seen so far, and it makes it really hard
to kill. For that reason, it's pretty powerful.
The effect is a bit weirder. Few sane opponents
would want you to draw three cards off of the
Gearhulk entering (unless they'd be at risk of
dying), so you'll rely on this being a 6/6 with
added burn. The burn mode is very variant,
though; as much as one might like to mill three
more Gearhulks and light them up for 18, that's
unlikely, and you're looking at this being a 4-7
damage swing in most cases.
I think the effect has potential, but even if it
doesn't, it's still a 6 mana 6/6 with first
strike. And that's a decent place to be.