Skill trees are the basis of leveling and customizing your character in NEStalgia. The skill tree menu unlocks at level 5 and at that point the player will be able to customize their character with the five points available. There are three ways to gain additional points:
Gain an experience level, which grants one point.
Progress through the plot of the game, which grants one point after completing the main quest connected to Verity's lighthouse and an additional point after completing the main quest connected to the Arctic's ice palace.
Spend 100,000 gold on a Greater Moon Blessing, which grants four points all at once.
As of v1.62 this allows for a maximum of 38 points to spend.
Fire Adept: Points in this branch allow a conjurer to make use of a fire-based damage over time spell (Simmer) and, eventually, a single target spell that will be familiar to fire-based wizards (Fireball). Fire Adept is a requirement for any build looking to focus on fire damage, although it is important to remember that conjurers do not have a way to reduce MP costs so their high damage spells will have high costs too.
Flame Span: Extra fire damage and fire resistance is nice, more so due to the boosts not increasing the cost of Simmer, Fireball or Boil, the last of which is learned from this branch.
Ice Adept: For ice-based conjurers, this branch provides all the benefits that Fire Adept does for a fire-based conjurer.
Cold Span: Like Flame Span, but with bonuses to ice damage/resistance and Chill instead of Boil.
Storm Adept: The last elemental branch in the spirit of Fire Adept, providing bonuses for a storm-based conjurer rather than a fire-based one.
Volt Span: Like Flame Span and Cold Span, but with bonuses and a spell for a storm-based conjurer.
War Mage: Additional amounts of intelligence can be helpful, but the bonus to agility is deceptively useful too when combined with the speed-boosting effect of the Shield spell. Shadows on its own is not a game changer, but the boost to success rate gained from Mind Control can make it a worthwhile tool for some builds.
Mind Control: Sleep is a powerful tool when used right, as can be Nightmare. Nightmare will provide most any conjurer build with a solid source of single-target burst damage, and the 12% boost to Sleep's success rate can ensure a successful attempt at delivering a terrible dream.
Sweeper: For any build that makes use of Boil, Chill or Spark, this branch is a great way to increase damage output without increasing the amount of MP spent.
Expert Healer: Any build that focuses on healing should spend at least four points in this branch, which will increase the potency of all Renew spells as well as unlock access to more powerful spells than the base Renew.
Blessing: The next step up in healing, this branch adds the RenewMore spell and allows the base round of any Renew spell a small chance of adding a beneficial effect to the target(s).
Lasting Recovery: Only the most dedicated of healing builds require investment in this branch, although any other build won't be harmed by having access to RenewMost nor by having the chance for their Renew spells to last for four ticks instead of three.
Amend: Healing conjurers will likely want to fill out this branch, as doing so reduces the cost of their Renew spells by a fair amount while also adding a way to heal every party member for a modest amount per tick.
Shepherd: This branch will lessen the need to gain +HEAL from equipment and seeds, potentially freeing up an equipment slot and/or multiple seed slots for other needs. The bonus to defense is minor at first glance, but similar to the agility boost from War Mage, this bonus is boosted when combined with the boost from the Shield spell. Dream is situational, but being able to wake any sleeping targets while also healing the entire party is quite handy in such situations.
Sound Mind: Vivify is an effective and inexpensive way to dispel sleep and confusion. Being more resistant to sleep and confusion makes it more likely to be in a position to use Vivify when needed. As expected, combining these two makes for a useful skill branch.
Second Coming: It takes a fair amount of skill points to get the full effect of this branch, but improving the usefulness of Redeem is a good thing for any conjurer who does not have access to Revive (or has already used the one charge of Revive on the Malevolent Orb).
Abilities are skills that the player can use both inside and outside of battle. These abilities will either be bought on the skill tree using skill points or will be learned automatically once the player hits a certain level.
Note: Listed MP costs are the default. Points in the Amend branch of the Healer tree will reduce the MP cost of renew spells: Renew, RenewMore, RenewMost, and RenewWave.