They must discard a card, or watch you place a Construct, Robot or Vehicle onto the battlefield
Aside from being a human, which is a very relevant creature type in Commander, Modern and basically every other MTG format, Esper Sentinel is good because it reads: Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays X, where X is Esper Sentinels power. Its a bit like Rhystic Study, but the cost can be far higher if youve got things that make humans stronger or you can put +1/+1 counters onto Esper Sentinel
are AI generated at minimum
This is exactly what theyve incorporated into Commander 2020 and I, for one, am a fan
To me it was just not the same as Pokemon where people literally fell in love with a certain Pokemon because of something in the anime, games or some other reason