Choose one -
• Target Dragon creature fights target non-Dragon creature.
• Until end of turn, target creature you control becomes a red Dragon with base power and toughness 4/4, loses all abilities, and gains flying.
• Sarkhan's Charm deals 4 damage to each player.
See Challenge # 144.
Aha, yes, nice. I looked at the name and thought "Hmm, needs to turn a creature into a Dragon. But can you do that in mono-red?" I'd forgotten that he turned RUG in his last incarnation, and of course blue is the primary colour of shapeshifting :)
The other two abilities seem very niche though. I think for 3 mana you could have "4 damage to each opponent", and the fight could easily be a full Pit Fight; I appreciate the extra words are for flavour, but it does make the card much less useful. How about "Target Dragon deals damage equal to its power divided as you choose among any number of target creatures"?