I think the idea is that you're only facing one person when your party can consist of up to four characters. My team of level 10 Hydrosophist / Geomancer / Polymorph with 1 provoking leadership tank did ok in Tactician. There's like 4 or 5 skills to buff your armour, good chance to dodge a couple of hits, and then I just freeze Murga. My tank still died once, admittedly. If you're weak when the other monster appears then you're probably screwed because the monster gets to act and cast a source spell straight away. If I were level 13 - 15, then I think Murga would've just fallen flat on her face.