Synapse Sparkcap

Action -

, banish an Evo from your hand: Create a Ponder token.

Battleworn

Rulings

From the Compendium of Rathe release notes

When paying the cost to activate Synapse Sparkcap’s activated ability, you must tap it and banish an object with the Evo subtype from your hand. When the activated ability resolves, you will create a Ponder token.
You cannot banish Singularity from your hand even though Teklovossen, the Mechropotent is its back-face. Even though Teklovossen, the Mechropotent has the Evo subtype, that face of the card is not its active face while it’s in your hand.

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.