It won't be put on the remaining legal target instead
That said, between ramps ubiquity in Commander, the fact that ramping one land for 2 mana has been good enough for many cards to see consistent play in the format for years, and the risk that Deep Gnome Terramancer will be a dead card is minimal at best, and Id call it a safe bet youll come out ahead far more often than not when playing this card
2 Thrasios, Triton Hero Sink All That Mana Commander 2016 brought with it a ton of incredibly powerful legendary creatures with the Partner ability, which lets you have two commanders so long as they both have partner
4 | Repurposing Bay Mana Value: 2U Rarity: Rare Type: Artifact Card Text: 2, Tap, Sacrifice another artifact: Search your library for an artifact card with mana value equal to 1 plus the sacrificed artifacts mana value, put that card onto the battlefield, then shuffle
Scry on attacks is the perfect way to rush towards the coveted piece of Power 9, and it lets you float past those perky Moxen you probably dont want to draw anyway
Vehicles was supposed to be a power-downed Equipment, which itself was seen as a problem as well