Serra Angel, Shivan Dragon, and Mahamoti Djinn were powerhouses back in the 90s (to the point where Serra Angel was left out of 5th Edition for being too powerful) , but they are far outclassed these days by Archangel Avacyn, Inferno of the Star Mounts, and Consecrated Sphinx
Prominent from the dawn of MTG, dragons have had a whole MTG set dedicated to them in Dragons of Tarkir, and even gave rise to the popular Commander format, otherwise known as EDH or Elder Dragon Highlander
Arena packs aren't exactly like usual Magic: The Gathering packs
For example, the above card has only the characteristics of Halvar, God of Battle in the graveyard, even if it was Sword of the Realms on the battlefield before it was put into the graveyard
Two new villains are also introduced, with Magica de Spell from the DuckTales franchise claiming hold of Tritons Trident and Jafar seeking out a new artifact called the Hexwell Crown
The replacement effect from Suplex's first mode will exile the target creature if it would die this turn for any reason, not just due to lethal damage
