Unwinding Finality (Red)

When this hits, draw a card.

Whenever this fragments, you may put a Lightning instant card from your graveyard on top of your deck.

Fragment

Rulings

From the Omens of the Third Age release notes

Unwinding Finality’s first ability triggers when this hits (e.g. heroes or allies). You will draw a card when the triggered effect resolves.
Unwinding Finality’s second ability triggers each time this card fragments (e.g. when its Fragment triggered effect resolves on the stack). This is an optional effect: You may choose and put a Lightning card with the “Instant” type from your graveyard on top of your deck when the triggered effect resolves.
Lightning cards without the “Instant” type but with instant-activated abilities in their text box (e.g. Amulet of Lightning, Lightning Greaves, etc.) cannot be chosen and put on top of the deck by this effect.

Keyword notes

Fragment - Whenever a card with 2 or more {d} defends this, this gets -2{p}

Fragment is an ability keyword.
Fragment will trigger each time a card with 2 or more is added as a defending card on its chain link. If multiple cards are added as defending cards at the same time (e.g. the defend step), the Fragment ability will trigger for each defending card being added that fits its triggering condition.
Fragment has an event-based triggering condition: its triggered effect will still resolve even if the defending card that triggered it has less than 2 or no longer exists at the time it resolves.
If a defending card doesn’t have 2 or more , and then it gets 2 or more , fragment doesn’t trigger because the card didn’t have 2 or more 2 at the time it was defending.
When a Fragment triggered effect resolves on the stack, that card with the ability fragments. A card that fragments can be used for the purposes of other cards and effects (e.g. “Whenever this fragments”). If there are multiple Fragment triggered effects on the stack, a card fragments each time one of those triggered effects resolves on the stack.
If a card or effect requires an object that has fragmented (e.g. attack that has fragmented), it is looking for an object where its fragment triggered effect has triggered and resolved.
A card still fragments if resolving the triggered effect would put the card’s to less than or equal to zero.
If a card gains Fragment while there are cards with 2 or more already defending it (e.g. Lunar Mirage), Fragment will not trigger retroactively. It will only trigger when additional defending cards that meet its condition are added to the chain link.