The total cost to cast this spell is locked in before you pay that cost
From Store Championship Promo Pack (Flame Slash)
In formats like Modern and Legacy, where efficiency is already a priority, this restriction was often trivial to meet, leading to a period of homogenization where nearly 30 percent of top-tier decks included Lurrus as a starting resource
Chernabog, Evildoer (205/204) Enchanted Rare ($167) One of the most striking villains in Disney history, Chernabog appears in the classical music-based 1940 film, Fantasia
Effects that switch the creatures power and toughness are always applied after any other power or toughness changing effects, including this one, regardless of the order in which they are created
Finally, the card draw and reanimation effects are inefficiently costed, even at instant speed, but that makes them far from irrelevant