The Coveted Shard

Whenever a historic permanent is destroyed, put
a charge counter on The Coveted Shard.
{3}, {t}: If you activated an ability of another legendary permanent you control this turn, proliferate.
{t}, Remove 25 counters from permanents you
control: Choose any number of nonland
permanents, then exile the rest. Shuffle The
Coveted Shard into its owner's library.