Its like a slightly worse Assemble the Legion, a virtually unbeatable rare that gives you a ton of free value over the course of a few turns
Actions and Items can take her out in that case, but not her allies, as Ward keeps them safe from anything that isn't a challenge
Urtet, Remnant of Memnarch You could pick another 5-color commander with minimal synergies, like Kenrith, the Returned King or even Kyodai, Soul of Kamigawa, but Urtet, Remnant of Memnarch can synergize slightly, especially if you keep Brudiclad, Telchor Engineer and the myr subtheme in the Creative Energy precon (which I wouldnt!)
They have no additional abilities, just efficiency
Attacking and blocking During your combat phase, you will attack your opponent with your creatures, and they will have the chance to block with theirs
Like most expensive MTG cards, Rhystic Study gets a lot of its value from its perceived power