Occasionally, a player will want to keep their hand, so theyll choose 0 as their number
The emphasis on spellcasters gives some of the most useful, including Magicians Valkyria, who draws fire from all other spellcasters on your side, and Skilled Dark Magician, who has 1900 attack and can be sacrificed when youve used three spells to summon Dark Magician
If two or more cards are tied for highest cost, the target or targets remain unchanged
These are the most consistent decks in Standard and the most played on the Arena Ladder: Izzet variations (prowess, elementals, lessons): These decks all play a lot of blue and red cantrips/burn/lessons to fill their graveyard and exploit synergies, like lessons in the graveyard, cost reduction, or elemental creatures
Its important to note that Frank is not describing the ideal number of sources for a given set of spells, hes describing the minimum , by his definition
5 cards of rarity Rare or higher