"Kicker [cost]" means "You may pay an additional [cost] as you cast this spell." If a spell's kicker cost was paid, the spell is "kicked." The kicker ability doesn't let you pay a kicker cost more than once
7 Death's Shadow Death's Shadow is an iconic mono-black creature that has a powerful namesake deck within the Modern format
Mega-Mega Cycles, on the other hand, have cycles that are completed in a completely different block to the one they started in, which means they can still happen (and do more often now that every set is considered its own block)
Thanks to lots of ways to warp, sneak, or flicker creatures in white this is relatively easy to pull of each turn
I don't mind the Blight mechanic at all, but it's barely made an impact on Standard play, and this deck just isn't quite on the same level as many of the others released so far this year