Whenever a creature attacks you, it loses
flankingFlanking is a triggered ability that triggers during the declare blockers step. (See rule 509, “Declare Blockers Step.”) “Flanking” means “Whenever this creature becomes blocked by a creature without flanking, the blocking creature gets -1/-1 until end of turn.”
If a creature has multiple instances of flanking, each triggers separately. (CR 702.25) until end of turn.
Whenever a creature without
flyingFlying is an evasion ability.
A creature with flying can’t be blocked except by creatures with flying and/or reach. A creature with flying can block a creature with or without flying. (See rule 509, “Declare Blockers Step,” and rule 702.17, “Reach.”)
Multiple instances of flying on the same creature are redundant. (CR 702.9) attacks you, this enchantment deals 1 damage to it.