For an outrageous seven mana, you also get to 'Time Travel' three times, a new mechanic, that's a little like proliferate, letting you add or remove time counters to all permanents that already have one
Players were often pressured to pass their turn and save expensive removal spells to prevent Crucias from triggering, and Crucias's stats were good enough to stave off attacks in the early game
The first is strong as you are tossing on two abilities and likely a counter onto a dork, and the next is a drain ability if you have a Vampire you want to give up for the cause of killing a dork or finish off a planeswalker you just attacked into
If you also attack with Phyrexian Dragon Engine, you still trigger Mishras attacking trigger, but then meld the two
Then create a Lander token
Salvager is mostly poo as it is sorcery speed sacrifice but it can at least do artifacts as well which has its place, most notably with Pitiless Plunderer