Johanna, Heir of Kjeldor

Haste, First strike
Whenever Johanna, Heir of Kjeldor attacks, look
at the top X cards of your library, where X is the number of attacking creatures you control. You
may put any number of creatures revealed this
way with total converted mana cost X or less onto
the battlefield, tapped and attacking. Put the rest
on the bottom of your library in any order.