Can you beat Mangar without the special trick? (early game minor spoiler)

Fairly early on in The Bard’s Tale IV: Barrows’ Deep, you get into a boss-fight style brawl with Mangar.

He has a lot of HP, armour and spell power, but

However, during my recent playthrough I was doing surprisingly well against Mangar conventionally — a 2H fighter cracked his armour down to zero, two spellcasters that could smack his Mental defenses every time he tried to meditate to recover HP, and AoE attacks to keep the totem spam manageabl — and I can’t help but feeling that it might have been possible to win that fight without resorting to the spoiled gimmick.

Is that in fact possible, and does it change the outcome WRT

?