You must pay any mandatory additional costs (such as sacrificing a creature) and you may pay any optional additional costs (such as kicker) for the card you cast
Ib Halfheart, Goblin Tactician is a great example of a card that breaks attritive parity whenever it is necessary to
Chief among those options is the Bruce Banner / The Incredible Hulk card, which you can leverage as a single blue mana Commander using the Bruce Banner side, before transforming it into The Incredible Hulk for six mana when the time is right
It can be recurred through effects like Sun Titan and Sevinnes Reclamation, is easy to tutor for with access to black in its color identity, and is going to be very easy to justify fitting into a variety of strategies that use black and white
Still, if youre playing in a meta where this card feels fair, and people run plenty of removal for it, then Glacial Chasm can really help you if youre a late-game control or combo deck
Personal Tutor : Similar to Mystical Tutor in only looking for specific card types, but it can only search for a sorcery card