Crashing Footfalls, Living End and Glimpse of Tomorrow are all stopped with a 0-mana Chalice of the Void other use cases for the card are for example disabling Lotus Bloom out of the Tameshi Bloom deck or preventing Affinity decks from playing their Ornithopter, Memnite, Welding Jar and co
A good spread of card types is great but don't get caught up on that, you don't need all of them and you don't need to have at least three of each
Devotion means counting up each colour pip (in the case of black, the skull symbols at the top right-hand side of our permanents) and adding up the total
Specifically in Commander, this card has some great link-up potential with cards like Willowdusk, Essence Seer, or Betor, Ancestor's Voice, which offer bonus actions based on the life lost (or gained) in a turn
You can run Keruga in a Simic deck or in any three, four or five-color deck that includes green and blue
Mutavault (NEW!)