Development of a Wizard hero from the Haven faction.

Magic Affinity is a completely useless bonus; 30 mana is unnecessary for spells costing 40+; we increase the amount of mana throughout the game using artifacts. Why do you need Regeneration? I always level up a light healer, which gives me excellent resistance with a bonus to initiative and a pretty good resurrection. As for Logistics and similar skills, it's purely a matter of taste; I level up Logistics last, especially now that there are so many possible teleports.
I haven't lost a single battle with a light healer in duels; I haven't had time to use it in regular battles yet. :)
And yes, you have interesting battles that last 3 turns, considering that in the Campaigns, they can last far longer than 10. :)

The game is great because you can complete it in so many different ways. So, without a doubt, you can complete the Campaign without Logistics.
I prefer to have 160+% skill and a high Hero level at the end of the map. So, speed, zero losses, and a large mana pool are clear priorities. :)

At the beginning of the Campaign, the Cleric has very little mana, and the map settings are "normal hero development," meaning experience is gained very slowly. Even if you find a well, you can only drink from it once a week. So, if you need more mana, you also need mana regeneration.
Without set items, you regenerate mana slowly – only 8 per turn with 80 mana. Increase this number by 30, and you get additional Healing "for free" and an additional 3 mana per day. This is great at the beginning of the Campaign, but later, these 30 mana may not be enough in a crucial battle to achieve zero losses. Verdict: you should take it. ;)

Logistics is interesting if you want to get a high percentage for completing a mission. The faster you complete it, the higher the percentage at the end. Plus, you get an achievement for completing it quickly, so why not?
Even on the third map of the Campaign, the speed of your main hero determines whether you will be able to capture the second city before the third week or whether you will be stuck with three Naga increases and have to wait another couple of weeks.

Regeneration is great when you want to complete missions in the Campaign without losses. Healing has a long cooldown, but you often need to quickly heal stacks before the battle ends. Mass regeneration is perfect for sieges – battles are long, usually more than 5 turns. So, using it on turn 3-4 allows you to have a full number of troops by the end of the battle. However, after level 15, it is best to drop Regeneration – battles become very fast, and losses are minimal.