While her employers and actions are occasionally questionable, she always fights for the future of humanity
Grim Return is certainly a unique card, and this type of thing is almost never unplayable
Just a flash, or in later games, a tiny stab, perfectly representing its First Strike and Deathtouch abilities when it attacks
It's a giant monster that arrives at instant speed, it can't be countered, and it bounces nonland permanents or spells on the stack whenever you cast something
With knights such a prevalent and supported type (there are over 500 cards with the knight subtype), it has more than earned its place as a viable archetype
Between the new(ish) strategies, twists on old mechanics, and clever new-to-Magic designs in each deck, theres always something interesting in these precon line-ups