Summon: Shiva: Her stun abilities make it likely that youll be able to get in an attack with her (and your other creatures), and her final ability means that you wont be down a card when she leaves the battlefield
If the creature with exploit isn't on the battlefield as the exploit ability resolves, you won't get any bonus from the creature with exploit, even if you sacrifice a creature
For this reason, its a pretty useful card to have in duels, if you have five ink to play it, of course
7th) Radiant Blastoise (GO TCG - 18/88) One of Charizard's main rivals, our turtle is on the podium
Minsc & Boo, Timeless Heroes I hesitate to call the second ability on Minsc & Boo, Timeless Heroes an ultimate, but it works so well as a sacrifice outlet that burns targets and gives you cards