Aotrix, Order Maintainer

Flying, Hexproof
Whenever a player casts their first spell each
turn, detain each nonland permanent your
opponents control with mana value X or less,
where X is the mana value of that spell. (Until
your next turn, those permanents can't attack or block
and their activated abilities can't be activated.)
When the higher ones speak,
those beNeath them must be silent.