Nadir Kraken

• WWizards of the Coast2020-01-24
  Official Ruling
  You choose whether to pay after drawing the card and seeing what it is. If you draw multiple cards, you see them all before deciding how many of the resulting triggers you'll pay for.
• WWizards of the Coast2020-01-24
  Official Ruling
  If Nadir Kraken leaves the battlefield after its ability has triggered, you can still pay and get a Tentacle, even though you won't put a +1/+1 counter on Nadir Kraken.
• WWizards of the Coast2020-01-24
  Official Ruling
  While resolving Nadir Kraken's ability, you can't pay multiple times to create multiple Tentacles or to give it multiple +1/+1 counters.

Rulings via Scryfall