Major Keyhoe, Eternal Claim

When Major Keyhoe, Eternal Claim enters the
battlefield create three clue tokens
Major Keyhoe, Eternal Claim gets a +1/+1
counter when you sacrifice a clue token for
the first time each turn.
You may pay {1} the first time you sacrifice a
clue each turn, if you do create a clue token
"Keeping Eyes on the Skies" since 1950