Head Stone

Instant - Destroy this: Destroy the top card of your deck.

Battleworn

Rulings

From the High Seas release notes · June 6 2025

Destroying the top card of your deck will not trigger any “when this is destroyed,…” effects unless it is specified by the ability’s triggering condition.
Destroying the top card of your deck will not satisfy any condition nor trigger any effects that look at whether you’ve destroyed an object you control (e.g. Merciful Retribution, Ratchet Up) as you do not control the cards in your deck.

Keyword notes

Battleworn - Equipment that wear down after each time they are used to defend. If you defend with a card with Battleworn, put a -1{d} counter on it when the combat chain closes.

When you defend with a card it remains on the combat chain until the chain closes, therefore you cannot defend with an equipment multiple times on the same combat chain.
A -1 counter stays on the card until the card is destroyed or the game ends.
If the defense of a card that is defending is below zero, its defense value is considered to be zero.
When this card is destroyed, it is sent to your graveyard. (Not when it has 0)
When this card is destroyed, it is sent to your graveyard.
If the defense of a card that is defending is below zero, calculate as if its defense is zero.