Heroes of the Realm cards are a strange set while lots of them are interesting, many of them are physically impossible to play to a degree that not even silver border cards are, such as transforming into a card from a completely different card game
For example, a bracket one deck can't have any two-card infinite combos and a bracket three deck can't have mass land removal
Plus it will remove your opponents ramp like their Sol Rings and other cheap manarocks boosting you even further ahead
Etali is unfortunately fairly vulnerable for a big dinosaur, and a kill-on-sight card in Commander, so you'll also want to have cards that provide Etali with haste, so it will at least have a chance to attack
They are so good that it is impossible to distinguish them from authentic Magic cards
360 is the minimum for 8 players, so thats ideal if you want a carefully curated experience