Teklo Foundry Heart

Once per Turn Action -

: Banish the top 2 cards of your deck. Gain

for each Mechanologist card banished this way. Activate this only if you have boosted this turn. Go again

Battleworn

Rulings

From the Arcane Rising release notes

You may only activate this once, even if you have boosted multiple times in a turn.
Since this is an action, the combat chain must be empty when this is activated. You may close the combat chain after your boost attack but before activating this)
You may use this even if you have less than 2 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.