Salvage Titan — ruling 1

To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as Salvage Titan's alternative cost), add any cost increases, then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.

Salvage Titan — ruling 2

Casting Salvage Titan by paying its alternative cost doesn't change when you can cast it. You can cast it only at the normal time you could cast a creature spell.

Salvage Titan — ruling 3

You may activate its second ability only if Salvage Titan is in your graveyard. To pay this ability's cost, you may exile any three artifact cards from your graveyard—including Salvage Titan itself. If you exile it to pay the cost, however, it won't be returned to your hand when the ability resolves.

Salvage Titan : règles, fonctionnement et interactions (MTG)

Salvage Titan is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

You may sacrifice three artifacts rather than pay this spell's mana cost. Exile three artifact cards from your graveyard: Return this card from your graveyard to your hand.

How it works : Salvage Titan

Original English text — Wizards of the Coast / Scryfall

#1August 7, 2020· Wizards of the Coast
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as Salvage Titan's alternative cost), add any cost increases, then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.
No other card is named in this ruling.
#2August 7, 2020· Wizards of the Coast
Casting Salvage Titan by paying its alternative cost doesn't change when you can cast it. You can cast it only at the normal time you could cast a creature spell.
No other card is named in this ruling.
#3August 7, 2020· Wizards of the Coast
You may activate its second ability only if Salvage Titan is in your graveyard. To pay this ability's cost, you may exile any three artifact cards from your graveyard—including Salvage Titan itself. If you exile it to pay the cost, however, it won't be returned to your hand when the ability resolves.
No other card is named in this ruling.