Sentry Bot Eliminator

As long as Sentry Bot Eliminator is
untapped it has indestructible.
Salvage 4 (Tap up to four creatures you control and
exile this from your graveyard. Artifacts you cast this
turn cost {1} less for each creature tapped this way.)
"These rigs hold all the high value components.
If you can get passed its defenses."
-Rust Devil scrapper