FlashFlash is a static ability that functions in any zone from which you could play the card it’s on. “Flash” means “You may play this card any time you could cast an instant.”
Multiple instances of flash on the same object are redundant. (CR 702.8)
CascadeCascade is a triggered ability that functions only while the spell with cascade is on the stack. “Cascade” means “When you cast this spell, exile cards from the top of your library until you exile a nonland card whose mana value is less than this spell’s mana value. You may cast that card without paying its mana cost if the resulting spell’s mana value is less than this spell’s mana value. Then put all cards exiled this way that weren’t cast on the bottom of your library in a random order.”
If an effect allows a player to take an action with one or more of the exiled cards “as you cascade,” the player may take that action after they have finished exiling cards due to the cascade ability. This action is taken before choosing whether to cast the last exiled card or, if no appropriate card was exiled, before putting the exiled cards on the bottom of their library in a random order.
If a spell has multiple instances of cascade, each triggers separately. (CR 702.85)
ReachReach is a static ability.
A creature with flying can’t be blocked except by creatures with flying and/or reach. (See rule 509, “Declare Blockers Step,” and rule 702.9, “Flying.”)
Multiple instances of reach on the same creature are redundant. (CR 702.17)
When this creature enters, put three +1/+1
countersTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on each of any number of target creatures that entered this turn.