Andor's Trail

Trick is to save in the vincinity of a group with 2/3/4 enemies very close to each other. Then load, go next to all 3, save. If one moved or attacked, reload, try again.
Doesn't take long, and you get a good save. Done it many times with up to 4 enemies.
Important: turn on "confirm attack" before you try. That way you can savely bump into them, cancel the attack and immediately save.

4 gargoyle guys or imps right next to you, and you can mass up kills insanely fast.

Oh, and in case you like min/maxing, you try to get the right angle as well
Since I use my right thumb, I make sure that at least one marked enemy is in the lower right corner of my character and bottom and right have a wall and another enemy. That way I have short tipping ways for my thumb and cannot accidentally walk past the mob.

Further min maxing: save in the save slot that is in the same spot as the "load game" option. For my phone it is slot 10.
That way, I only need to open the menu and then click in the same spot 3 times rapidly in a row and voilla, back in combat (load game, select slot, attack)
You cannot kill faster manually

Shadowfang? Note that the actor condition it applies is on source, not on target

Shadowfang has the best name of any item in the game, but it is a pretty useless item.

I think I like the name "Gleaming claymore of ruin" more, and it's not a useless item

Yes, that is a good one. I like "shadowfang" because it reminds me of wolves which I love.