I was wondering about the interactions between Razaketh, the Foulblooded and Black Sun's Zenith. If I cast Black Sun's Zenith, choosing at least 8 for X, can I use Razaketh's ability to tutor for Black Sun before he dies?
The State-Based Action that would put Razaketh into the graveyard happens the next time a player would get priority after Razaketh gets the -1/-1 counters, so it happens before you get priority to activate Razaketh's activated ability.
The last chance you have to activate Razaketh's activated ability occurs before Black Sun's Zenith starts resolving, and Black Sun's Zenith isn't in your library at that point.
If Black Sun's Zenith was an instant (or gained flash), then you could make it work. You'd start by activating Razaketh's activated ability, then cast Black Sun's Zenith in response. Black Sun's Zenith would resolve first, then Razaketh would die, then Razaketh's activated ability would resolve.
No, you cannot look for Black Sun's Zenith when playing it and activating Razaketh the Foulblooded's ability.
To see why, let's look at the stack:
- You play Black Sun's Zenith: this means paying its cost and placing the card itself on the stack. As per the rules:
601.2. To cast a spell is to take it from where it is (usually the hand), put it on the stack, and pay its costs, [...]
- Before the X -1/-1 counters are distributed, you activate Razaketh's ability. You can't do it after, because Razaketh will be gone by then if we assume Zenith's X is 8, as you propose:
- State-Based Actions [...]
704.5f If a creature has toughness 0 or less, it’s put into its owner’s graveyard. Regeneration can’t replace this event.
- Razaketh's ability resolves first, but since Black Sun's Zenith is still on the stack physically, you can't look for it in your library.