Attacking is the last action you can do on your turn
These cards can be played in Limited (Draft and Sealed Deck) formats that include Murders at Karlov Manor and can be played in other formats (Pioneer, Modern, Commander, etc.) where they are already legal
I still remember the first time I played the Modern Up the Beanstalk deck with the evoke Elementals and just how absurd it felt being able to chain together free spells while drawing your entire deck, disrupting your opponent, and killing their board
So my keen powers of analysis are under, well, my own curse
SIR Umbreon was a rare card to begin with, but that double scarcity, and being arguably one of the most beautiful modern cards released, is the reason why this card is currently worth just under $1000
Dont let the Discard pile worry you though, there are many cards that allow you to retrieve certain cards from the Discard pile and bring them back into the game