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)
This creature can't block.
Whenever this creature deals combat damage to a player, they get that many
rad countersRad counters are a kind of counter a player can have (see rule 122, “Counters”). There is an inherent triggered ability associated with rad counters. This ability has no source and is controlled by the active player. This is an exception to rule 113.8. The full text of this ability is “At the beginning of each player’s precombat main phase, if that player has one or more rad counters, that player mills a number of cards equal to the number of rad counters they have. For each nonland card milled this way, that player loses 1 life and removes one rad counter from themselves.” (CR 728.1).
Whenever an opponent mills a nonland card, if this creature is in your graveyard, you may return it to your hand.