Using Stay to ensure a pet diesFollow

I'm a 15bst/whm taru, and I want to use the Stay ability to make sure my pet dies.

Here is the scenario: suppose I pit a decent against an even, or an even against an even. Most times my pet will die, and I finish off the match. However, sometimes my pet does better than I expect. If it wins, I'm left with a nearly useless pet with very low hp. I'm not casting or meleeing during the fight.

If I use Stay alone, it keeps fighting, which doesn't help. I can use Heel followed by Stay, but somehow this draws agro, so I get a mob attacking me, and my nearly dead pet standing by.

Is there a way to get this to work?

I asked a GM about this one time because I thought the game was glitched somehow. Most of the time when you heel your pet, he runs back to you, the monster takes one shot at you, then finishes off your pet. Sometimes however (although the frequency seems to be lessening as I level up and raise charisma), the monster just focuses on you and ignores your pet. When I talked to the GM, he said that when you heel it has a certain percentage chance (depending on stats and level, I guess) to completely wipe your pets aggro and dump it onto you.

You can't really stop that from happening, so the easy solution if the monster attacks you more than once is just kill it, then send your almost dead pet against something else until it dies, then charm that monster. The new, kind of hurt pet will almost assuredly die fighting another even and you're good to go.