If the target creature is an illegal target as Vitu-Ghazi Inspector's triggered ability tries to resolve, it won't resolve and none of its effects will happen. You won't gain life.
2024-02-02 • wotc
If you can't exile enough cards to meet or exceed the required mana value, you can't choose to collect evidence at all.
2024-02-02 • wotc
Once you've announced that you're casting a spell, players can't take actions until you've finished doing so. Notably, opponents can't try to remove cards from your graveyard to stop you from collecting evidence.
2024-02-02 • wotc