Finally, Red + Green Burn tends to punish what Green hates, namely all-things winged or artificial (Clan Defiance, Cindervines, Ruric Thar, the Unbowed, etc.), or staples Burn onto already-useful effects (Vengeful Rebirth, Exploding Borders, etc.)
The Pokemon TCG Mew VMAX League Battle Deck is the best way to enter the competitive scene for newcomers
And its not even an Un-card
For example, my own Mazirek, Kraul Death PriestMazirek, Kraul Death Priest deck (which I'll be showing off shortly) has several creature-based sacrifice outlets, such as Viscera SeerViscera Seer, Bloodthrone VampireBloodthrone Vampire, Bloodflow ConnoisseurBloodflow Connoisseur, Dimir House GuardDimir House Guard*, and Sadistic HypnotistSadistic Hypnotist
In formats like Commander, this card is very common