Landfall — Whenever a land you control enters, you may have target player lose 3 life. If you do, put three +1/+1 counters on Ob Nixilis.
Play extra lands to drain opponents 3 life at a time while Ob Nixilis snowballs into a massive, evasive threat. You want fetch lands, land-into-play effects, and ways to replay lands so each landfall trigger both grows your commander and burns a chosen player. Close games with commander damage or by draining the whole table to death.
Each landfall hits any target for 3 life and adds three counters—doubling as removal-proof reach and a fast clock
Mono-black gives the best tutors, ramp, and recursion in the format
Fetch lands and free land drops make him a 9/9+ as early as turn five
Drain damage ignores blockers and creature-light boards, punishing defensive opponents
He has no built-in evasion or protection, so commander damage stalls behind blockers
Heavily reliant on the commander itself—if he's repeatedly removed the deck loses its engine
Mono-black struggles with enchantment and artifact removal
Slow without explosive landfall enablers; a single land per turn only drains 3