RAW, i don't think that works, since the enemy isn't doing anything - YOU'RE the one who's acting. thus, the enemy isn't entering anything. this is usually how effects like spirit guardians work, anyway (which is also why they specify the effect procs if a creature starts their turn in the...
extra attack specifies that it only works on your turn. thus, readied attack actions are only ever one attack, because they are not on your turn.
it is, however, still essentially a free attack, which is still solid.
EDIT: i just saw your "my turn" situation. im not really sure that could...
frangibles, yeah.
"Pistols put holes in people. Rifles put holes through people. Shotguns, at the right range, with the right load, will physically remove a chunk of $#!% off your opponent's body and throw that $#!% on the floor!"
well, swat teams largely like them for breaching doors and the variety of ammo types (especially less-than-lethal) that can be fed into them. their stopping power in close quarters is definitely part of it though.
...if i had a nickel for every backerkit project for which i was seemingly part of the smoke test, i'd have 4 nickels, which is actually a lot all things considered.
you need an amulet AND a SET of rusted iron rings to shift into the bleak gate, and even then it only seems like it's a partial shift. so the players can TRY to get into the bleak gate using iron rings and an amulet, but they won't get all the way there.
i'm--pretty sure that'd be grounds for a lawsuit. if the offended player would be so inclined to pursue such a thing. would be an amusing use of downtime.
i don't actually think you'd get flanking even if you landed in a flanking position, since the check is made during the jump, and either way the check is initially to JUMP, not to attack the target. i don't think it'd be unreasonable for a narrator to give the flanking bonus, but RAW i don't...