Sicken

The cycling clause is what saves this from being a sideboard card that rots in your opening hand. A flat -1/-1 aura is among the narrowest things black does: it kills the one-toughness creatures of its day and trades down against nearly everything else, so most of the time the aura would sit dead, waiting for a target that may never come. Cycling answers an old design problem with narrow effects: how do you give a player a cheap creature-debuff without punishing them when the opponent fields nothing worth shrinking. The floor stops being a stranded enchantment and becomes "two mana, draw a card." You keep the option to point it at an X/1 when the board demands it, and you discard it for replacement when it doesn't. That conversion of a marginal removal spell into an on-demand cantrip is the structural innovation the cycling cards of this era pioneered, smoothing the variance of situational answers by giving every dead copy an escape hatch. Sicken sits at the humble end of that lineage: a debuff aura that asks almost nothing, returns a card when it has no job to do, and never fully wastes the slot it occupies.