Gravity Well
Rise of the Eldrazi — uncommon
Enchantment
Gravity Well rulings:
2010-06-15: This ability triggers and resolves during the declare attackers step. The creature will no longer have flying by the time blockers are declared.
2010-06-15: After attackers are declared and any Gravity Well abilities have resolved, a spell or ability that grants flying to a creature will work normally. This includes other abilities that trigger “whenever [a creature] attacks” (such as the one Order of the Golden Cricket has).