Ishil, The Horrid

Ishil, The Horrid costs X less mana, where X is the number of legendary creatures in your graveyard.

Myriad. (Whenever this creature attacks, for each opponent other than defending player, you may
put a token that's a copy of this creature onto the battlefield tapped and attacking that player or a planeswalker they control. Exile the tokens
at the end of combat.)

The Beast lurks below, eagerly awaiting those who are foolish enough to enter the Shadow Isles.