Hierophant Bio-Titan
Creature — Tyranid
Frenzied Metabolism — As an additional cost to cast this spell, you may remove any number of +1/+1 counters from among creatures you control. This spell costs 
less to cast for each counter removed this way.
Vigilance, reach, ward
Titanic — This creature can't be blocked by creatures with power 2 or less.
David Astruga
Rulings
Heirophant Bio-Titan's first ability can't reduce its cost below {G}{G}. You can remove any number of counters, even if they won't reduce its cost any further.
(wotc • 2022-10-07)
Once a creature with power 3 or greater has blocked this creature, changing the power of the blocking creature won't cause this creature to become unblocked.
(wotc • 2022-10-07)
Rulings
Heirophant Bio-Titan's first ability can't reduce its cost below {G}{G}. You can remove any number of counters, even if they won't reduce its cost any further.
(wotc • 2022-10-07)
Once a creature with power 3 or greater has blocked this creature, changing the power of the blocking creature won't cause this creature to become unblocked.
(wotc • 2022-10-07)