Yeah, its decent, not great. Personally i focused entirely on defensive stats on all gear, and i had no problem killing anything.
Here are the offensive stats on my gear put together:
+39% fire dmg
+25% fire penetration
+10% physical penetration
+8% physical dmg
+15% lightning penetration
Most of the fire stuff is from my weapon, the rest, except the str, is from random pieces i wore for their defensive stats. You can see which attribute i focused on getting, and really, i think its the most efficient and easiest to get by far. Str will buff the damage of all your breaths across the board, on all enemies, always, whereas % elemental modifiers only buff 1 breath each, which in the long run hardly makes a difference. % penetration is nice if its convenient (so on an item you would wear even without the penetration), but it only does something if the enemy has that particular resistance, in addition, since you already get 20% penetrations from chromatic fury, immunities are broken already, and you need a lot on top to actually make a noticeable difference from there. All in all, getting penetration is just horribly inefficient for a build that uses 6 different damage types. I would only get penetration if its very high, or if the item has several penetration types. % elemental damage can be good, since the str bonus is flat and will then be multiplied, but again, only noticeable if you have a decent amount and only on one breath. Again, get it if its convenient or if it applies to several elements, or there is a lot of a single element, otherwise it wont make a practical difference.
Also remember, if you are thalore, the wrath of the woods will buff breaths by a percentage amount across the board, and with heroism on top, you wont
be needing for damage. You could have zero offensive bonuses besides str, and still have no problem with the final boss fight damage wise. I will say that my fire breath did considerably more damage than the rest, but across a 6 or 7 turn period, it makes no real difference
Strength is just so incredibly efficient for this build. With a high base str, str based heroism, wrath of the woods, as well as the 10% elemental dmg bonus from chromatic fury, you dont need any
more boosts for your damage. Not on normal anyway.
Of course, thats just how i chose to play
You could surely do it differently and be effective too, but i do attribute the ease with which i won to having maxed resists, 100% stun and confusion resistance, as well as 2k hp.