Technically speaking, its legal to play with a deck of more than 60 cards, but at all times your deck must be at least 60 cards and your sideboard must be at most 15 cards
As most creatures with this ability connive when entering the battlefield, this ability is at its best when you can blink permanents like Raffines Silencer constantly
On Play, it can give 1 of your Leaders +2000 power until the start of your next turn, and you cant add Life cards to your hand (at least, not with your own effects) during the same turn
Brain Maggot, Kitesail Freebooter, and Yaroks Fenlurker combine with one of the best spells in the format in Thoughtseize to ensure that we can rip our opponents hand apart before they get to do anything with it
Non-foil versions of the card are now trading for $8-10, thanks to a new Boros energy deck made possible by cards printed in Modern Horizons 3
In the higher-priced range, several synergy pieces like Harmonic Prodigy and Determined Iteration both increase the overall reprint value and differentiate this Spellslinger brew from other takes on the archetype