Only exerted characters can be challenged, so leaving them ready is a way to keep them safe
All I can say is, you better hope you have some enchantments that can help you rebuild
It takes just three turn cycles to trigger this in Commander, assuming you dont add counters, so you have the time and mana to set up leaves the graveyard synergies or similar effects
When you do, cast it for its madness cost or put it into your graveyard.) Enchantment Discard (CTRL to add secondary) Draw Ancestral Knowledge Cumulative upkeep (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) When this enchantment enters, look at the top ten cards of your library, then exile any number of them and put the rest back on top of your library in any order
Diablo is arguably the single strongest character released in the game to date, and the player market can have a huge impact on a cards value