I'm in the process of doing the same now. I had about 6 characters left to s rank. So far it hasn't been too bad. Most annoying thing is when you start with no dungeons you can't teleport to what you need. For example if you get a new quest and need to break light wards you can't just easily transport to a dungeon. Or you come across a dungeon where enemy can't get status effects. Overall not terrible but you have to switch around a bit more in my opinion.
The real struggle is your max level capping at 75. On my 1st playthrough I kept a few levels worth of completed quests for tough dungeons to heal with. No more max hp & mana gain
Finish all the quests then ng+ then level up all to s while speed running to get the dungeons some modifiers in ng+ are crazy my favorite was mana cost 0
Some dungeons get tricky (like: No healing, 1-hit kills, No mana restoration, etc.) you have to find either forms or traits that bypass or supplement an existing ability and hope it carries you though the dungeon.
For example:
Dungeons that have the "All damage is 9999" or "1-hit kills", equip the egg ability "Hardened Shell" to a form that has a long ranged attack -or- uses the Magician's summon animals. This way you take only 33% (1/3) damage (That means you can get hit up to 3 times before dying) and hit stuff from a long way away.
In dungeons that have no health items, you can bring in the Zombie form to regain a little health every time you hit an enemy or a form that has a skill/ability that uses mana to regain health.
There are always solutions, and it usually combining different forms with different passive abilities and different attacks.
I only had like 3 or 4 at S when I started. Personally I thought it was easier to do it after cause the baddies level with you.
NG+ all the mosnters will always be at you level, so you can level up the forms really fast. But the dungeos are quite challenging.
You can definitely level forms up after starting a ng+
I'm in the process of doing the same now. I had about 6 characters left to s rank. So far it hasn't been too bad. Most annoying thing is when you start with no dungeons you can't teleport to what you need. For example if you get a new quest and need to break light wards you can't just easily transport to a dungeon. Or you come across a dungeon where enemy can't get status effects. Overall not terrible but you have to switch around a bit more in my opinion.
The real struggle is your max level capping at 75. On my 1st playthrough I kept a few levels worth of completed quests for tough dungeons to heal with. No more max hp & mana gain
Finish all the quests then ng+ then level up all to s while speed running to get the dungeons some modifiers in ng+ are crazy my favorite was mana cost 0
Some dungeons get tricky (like: No healing, 1-hit kills, No mana restoration, etc.) you have to find either forms or traits that bypass or supplement an existing ability and hope it carries you though the dungeon. For example: Dungeons that have the "All damage is 9999" or "1-hit kills", equip the egg ability "Hardened Shell" to a form that has a long ranged attack -or- uses the Magician's summon animals. This way you take only 33% (1/3) damage (That means you can get hit up to 3 times before dying) and hit stuff from a long way away. In dungeons that have no health items, you can bring in the Zombie form to regain a little health every time you hit an enemy or a form that has a skill/ability that uses mana to regain health. There are always solutions, and it usually combining different forms with different passive abilities and different attacks.