Hierophant Bio-Titan — ruling 1

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.

Hierophant Bio-Titan — ruling 2

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.

Hierophant Bio-Titan : règles, fonctionnement et interactions (MTG)

Hierophant Bio-Titan is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

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. Reach, vigilance, ward Titanic — This creature can't be blocked by creatures with power 2 or less.

How it works : Hierophant Bio-Titan

Original English text — Wizards of the Coast / Scryfall

#1October 7, 2022· Wizards of the Coast
Heirophant Bio-Titan's first ability can't reduce its cost below . You can remove any number of counters, even if they won't reduce its cost any further.
No other card is named in this ruling.
#2October 7, 2022· Wizards of the Coast
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.
No other card is named in this ruling.