The Elder Scrolls: Legends Subcategories
I'm not as sure LL or NTL will get the wording change as these are a bit more complex. Complex enough that it might not save much space, assuming their functionality doesn't change.
Furthermore, I don't think either of those would be rewritten verbatim as you have it here. If I was incorporating the Slay keyword, it would be more along these lines:
Lucien Lachance: "... While Lucien Lachance is in play, all other friendly creatures have Slay:+2/+2." (The way you have it written, it would be permanent. And applied to enemy creatures as well.)
Night Talon Lord: "... Slay: Summon the creature(s) slain. (While I think everyone would understand what you have written, it just doesn't sound right to me to use "that" without first mentioning what it is referencing.)
They are random, if you mean the ones with specific names then some people have taken the time to use control decks to mill the opponent and find that out. Some are on UESP but many are not and would require a very well made deck and probably 30-60 minutes of time to figure out (assuming you don't die either ha).
You can't find them in the game though, you'll have to browse them interwebs though to learn more!
List of end of Season reward Cards:
January 2017: Stampede Sentinel
February 2017: Heroic Rebirth
Updated the list, also added March reward