Garden Tomb is read from the perspective of Garden Tomb's holder. Let's call that player Gabe. Let's call the other players Tim and Mike.
Gabe has Garden Tomb.
Tim has a Redeemed Soul.
Mike has NO Redeemed Souls.
Gabe's heroes ignore while attacking Tim, obviously.
If Mike attacks Tim, then neither player is Gabe's current opponent, so Mike's heroes don't ignore.
If Tim attacks Gabe, then since Gabe's opponent (Tim) has a Redeemed Soul, then Gabe's GT makes Tim's heroes ignore Gabe's EC.
If Mike attacks Gabe, then since Gabe's opponent (Mike) does NOT have a Redeemed Soul, then GT does not apply.
The only "your" on GT is in front of "opponent". It can be ANY player's hero, but only while YOUR current opponent has a Rescued Soul.