There's an argument against essentially forcing players to carry around periphery items to track their cards correctly, but innovations like dungeons and ability counters already do this to some degree
Oreskos Explorer : Allows you to search for a number of Plains equal to the number of opponents who control more lands than you and put them into your hand
Rather, it is best answered by playing some games and testing the numbers
The full version is buffing your team, giving you an extra combat step, and netting you a ton of treasures for making contact with the enemy
For two mana, you get a Blue 1/3 that makes Instant and Sorcery spells cost one less to cast
As with our prior top 10 lists like this, we will only be using the base version of cards and wont be counting alternative artwork treatments (this prevents 40% of the list just being variants of Hidetsugu, Devouring Chaos)