At the beginning of each players draw step, that player exiles the top card of their library
Eris also has flying and prowess, but the most important thing is: Once it's on the battlefield, whenever you cast your second spell each turn, it creates a 4/4 red Dragon Elemental token with flying and prowess
I have placed it very high up on my own list as well, but I am not sure whether I really think it is better than Veil of Summer or Force of Vigor, given that it is just a dumb, head-through-the-wall type card and the others are very specialized but devastating interactive cards
More than just the commander could see a bump from new relevance vis-a-vis being more fetchable
Because people like me, presumably, are a good slice of Wizards of the Coasts target demographic
Additionally, in the case of Dragons, there are also cheaper spells that reward you for playing Dragons in your deck