You dont have to cast it if you dont want to, and you dont lose it if you choose not to cast it for a turn or two
B/U Zombies springs to mind with Call the Bloodline, Haunted Dead, and Compelling Deterrence
This red enchantment is just good as a helpful piece of burn-based interaction in an energy deck in EDH, and it also burns out the table once you get one of the many infinite energy combos the top-tier of energy cards can shuffle together to generate
Forsworn Paladin has an extra ability that gives creatures Deathtouch, which can play a huge role in certain match-ups
Alongside Exhume in the Legacy reanimation deck, this card is used to put creature cards like Griselbrand, Archon of Cruelty, and Serra's Emissary into play as early as turn one
For example, while you cant earn any more of the last set's Mastery XP or rewards, you can still spend any unspent mastery orbs that you had already earned up until the next set releases on MTGA