I thought about upping the cost, for all of the reasons previously stated (don't wanna overshadow Otyugh and it seems a little too cheapo for a 5|5). But let me go through my math and you guys can poke the holes where you see fit

Unupped:
+3

for attack
+2

for either ability, assuming your mark matches
-1

for Life's innate bonus.
Upped:
+5

for attack
+2

for either ability, again assuming your mark matches
-1

for Life's innate bonus
-1

for Upgrade
Note: It also needs to remain cheap enough to stand as a viable vanilla creature for mono-Life.Hence why I thought the creature's element may need to change. I did think a boost to cost might be required at first but thought I'd toss it out as is and see what I can see. As for the art, follow the link in the Art section of the table and you can see the original image is a photo of a Chimera statue (another creature that might follow this treatment). Most of my pictures are photos that I've cropped, warped or run thru various filters. This was a hard one. If anyone wants to draw me a snarly little Manticore, complete with scorpion tail, it'd be most appreciated.
Know what might happen if a player has a
mark but owns a
mark card and plays it? 
Your mark, not your mark card

...if your mark changes mid-game, so does the Manticore (assume it happens at end of turn).
Also, the Griffin is a bird/lion thing. Close but not quite.