Serendib Djinn ($152) I wouldnt blame you if you thought Serendib Djinn was a 2-mana spell, but thats just how the print looks
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
By taking preventive measures, you can extend the lifespan of your cards, ensuring that they remain in top condition and ready for battles or trading
Further ahead, I bring tables with the information of each rank and prizes
How much is a 1st Edition Shadowless Charizard worth