A new cycle of rare spells in Ikoria: Lair of Behemoths give you a little if you pay for them easily, but a whole lot if you meet a certain mana cost. Check out the Mythos spells named for the legendary creatures in each wedge, all with stunning art from Seb McKinnon.
Mythos of Snapdax hearkens back to a combination of Cataclysm and Tragic Arrogance, allowing you to completely destroy your opponent by making all the decisions if you paid for it with BRWW. It allows Bant and Azorius decks to have a decent option, but is super charged in a Mardu deck.
Mythos of Nethroi on the surface is a simple Murder or Terminate substitute (with the exception of it not being able to hit creature-lands), but turns into a single-target Maelstrom Pulse when paid for with GWB. It’s an easy to splash removal spell that gets a lot more flexibility given it’s played in an Abzan deck.
Mythos of Vadrok is a juiced up Arc Lightning, splicing five damage for four mana, which is already great, but does so much more when paid for with WURR. Detaining a mob of creatures from an alpha strike, stopping an opposing team from attacking you, or even just preventing planeswalkers from activating are all options with this powerful sorcery.
Mythos of Brokkos is the oddest card in the cycle, acting as a double Regrowth (though only permanents) for its easy mana cost, but tagging on Entomb if paid for with Sultai mana. Diabolic Tutor rarely sees competitive play, but perhaps adding another piece of card advantage on the spell can give Mythos of Brokkos the push it needs.
Mythos of Illuna fits right into the long line of blue spells that copy permanents, but turns into a removal spell as well when paid for with Temur mana. Four mana to copy a creature and have it fight down an opposing threat is a solid deal and looks well-situated for the type of decks the Temur cards in Ikoria will enable.