Survey Mechan

• WOTC Official Reminder Textofficial rules
  Hexproof — This permanent can't be the target of spells or abilities your opponents control.

• WWizards of the Coast2025-07-25
  Official Ruling
  To determine the number of differently named lands you control, count each land you control once, but only if its English name isn’t exactly the same as another land you’ve already counted this way.
• WWizards of the Coast2025-07-25
  Official Ruling
  Use the sacrificed creature’s power as it last existed on the battlefield to determine how many cards to draw with Susur Secundi’s last ability.
• WWizards of the Coast2025-07-25
  Official Ruling
  Once you announce you’re activating an ability, no player may take actions until after the ability has been paid for. Notably, opponents can’t try to remove lands you control from the battlefield at that time.
• WWizards of the Coast2025-07-25
  Official Ruling
  Once you determine the cost to activate Survey Mechan’s last ability, you may activate mana abilities to pay that cost. If the number of differently named lands you control changes while activating mana abilities (probably because you sacrificed one or more lands), the cost to activate the ability remains what you previously determined.

Rulings via Scryfall