Phytohydra

• WWizards of the Coast2005-10-01
  Official Ruling
  If another effect would prevent damage from being dealt to Phytohydra or replace it with something else, Phytohydra's controller chooses which effect to apply first.
• WWizards of the Coast2005-10-01
  Official Ruling
  If Phytohydra blocks or is blocked by a creature with first strike or double strike, Phytohydra will get the counters during the first-strike combat damage step before it deals its own combat damage during the second combat damage step.
• WWizards of the Coast2024-01-12
  Official Ruling
  Phytohydra's ability doesn't prevent damage. Damage that can't be prevented will still be replaced by +1/+1 counters being put on Phytohydra.

Rulings via Scryfall