There are quite a few websites where you can create custom cards but mtgcardsmith.com is my favorite and what I used for the example card above
When purchasing storage boxes, binder pages, or any material that will be in prolonged contact with your cards, verify that the product is explicitly labeled as archival-grade or acid-free
Their strongest plays still require setup, and their win conditions are usually visible enough for opponents to interact with
Many of the planeswalkers have a kill switch and can be removed permanently if necessary, and Dragonlord Silumgar does that for us
Myr Enforcer, Myr Galvanizer, Myr Propagator, Myr Retriever and Myr Welder are all in the list, along with the eminently playable Myr Battlesphere