Soooo getting a pet to level 15 and killing people is pretty easy lolol
I'm afraid so. I've not had the time to fully test this, as I've been off on the City of Heroes closure protests in game when I've had free time, and I'm not willing to test on people who are unwilling to be attacked in the name of Science... but Nimuaq and I did a little experimenting before we got pulled in by a Call To Arms, and the rough details seem to be this;
1.) Reflection of damage appears to be about 40-60% above damage taken, so a Level 10 pet with approximately 500 hit points (depending on type) will easily out-tank any player attempt to kill it... in theory it should be possible to kill it with player damage all the same but in practice it's going to be too difficult I think.
2.) Direct damage fields, such as Fire Field do reflected damage. Indirect fields like Poison won't reflect damage, or possibly at 70s resist armor you won't take any. However each tick of poison and each stepping into the field will reveal you if you are hidden.
3.) Pets will automatically go for the damaging player when he attacks them, turning them grey still. And they hit HARD at high levels. I was taking 40-50 hit point damage from Nim's L8 pet with all 70s armor
Here come the parts I wasn't willing to test on the innocent...
4.) I'm not sure if turning a pet grey flags the pet also to a Party or Guild of players too.
5.) I don't know yet if your attacking a Player's pet allows your own pet to go for theirs, or for the player themselves. If it does, you can now PK in Trammel pretty easily as suggested with a L15 pet. Never conscript it and it'll never go to Call To Arms either.
6.) Any attempt to attack the pet which is attacking yours will more than likely kill you instead. This will happen irrelevant of the previous points, due to point 1.
7.) And here's the loophole I suspected was there; even if you can't get the pet to go for the player, either through automatic attacks or from him wildly shooting the pet attacking his, you can prevent anyone getting any pets to the opposite Karma zone by leashing a L15 pet, set to Aggressive, to either the moongate or to something nearby. Cast poison field all over the gate so anyone coming through instantly flags to the pet, and it gets killed by the L15 waiting. Move off screen so you can't be targetted by lots of pets coming through at once, and the poison fields won't reflect any damage back towards you.
As I say, this needs to be tested still, but if I have time tonight I'll get some volunteers to try and run the gates at a quiet time for the server and see if I can confirm how much annoyance or even death is possible...