Regenerate

The keyword that ate this spell is the reason it reads as a curiosity today. Regeneration was once printed out longhand on dozens of cards before the game compressed the whole replacement effect into a single word and a shield symbol, and what you have here is that effect sold separately: an instant that grants the protection without a body attached. The strategic axis is the destruction window. Cast in response to a removal spell, a blocking decision, or a board wipe, it converts a dead creature into a tapped one, which is why it answers targeted destruction and combat trades but does nothing against exile, bounce, sacrifice, or minus-toughness effects that drop a creature to zero. That gap is the whole tension of regeneration as a mechanic: it reads as a catch-all save but is actually a narrow one, and the years since this kind of effect was common have steadily widened the removal that walks straight past it. The single regeneration shield also expires at end of turn and protects against only the next destruction, so a second Wrath gets through. As a standalone instant rather than a stapled keyword, it trades flexibility (any creature, at any moment) for the inefficiency of spending a card and two mana to keep one creature alive once, which is most of why the design philosophy moved toward baking the protection into the creatures that wanted it.