On the new-card side, Shard of the Nightbringer is the one people want, an 8/8 flyer that drains half a players life when it lands, with Biotransference and Their Name Is Death rounding out the flavor-meets-function picks
Lots of these cards have special art but the normal frame, or maybe a retro frame, or perhaps a special foiling over a normal frame
That damage may cause Toralf's ability to trigger again
Or pick the option with the least pain
The only real times I would want to splash other non-red colours is when I didn't get enough playables in green and needed to make up numbers
While is pretty steep for a 5/3 creature, when it enters, its first chapter destroys target creature a foe controls, its second chapter is the your foe loses the game one, which is obviously awesome, and the third chapter draws you two cards and forces all players to lose two life