You can't activate it without a target in order to return Chthonian Nightmare to your hand
You may play those cards for as long as they remain exiled, and you may spend mana as though it were mana of any color to cast them
For this mini guide, I'll be referring to these lands: Cheapest: Trilands, Vivids This is the classic tried-and-true method to make a 5C manabase on a budget
So far we dont have answers to some questions, for example, whether you should play Burning-Tree Emissary or Clarion Spirit and Jegantha instead, whats the best way to utilise flex slots, or even how many lands the deck should play
Primeval Titan produces way too much mana while it tutors value lands and Golos is an obnoxious commander because the free land makes it nearly impossible to kill
You have to keep coming up with unique dog names each turn, which can be a fun challenge