This works in concert with poe currency ability gems, which slot into parts of gear and give your character charms and skills to use in combat (unlike Diablo 3, they don't have any provided abilities). Items will frequently have multiple gem slots, and sometimes they are linked together. If I put an ability like Orb of Storms into a slot and then join it with Curse on Strike, Flammability and Vulnerability, each moment my Orb of Storms hits an enemy it will also apply both of those curses into them. It's essentially a highly robust spell-crafting system.
Nevertheless, it's when ability gems and the tree float that things get very exciting. My Necromancer relies solely on Scorching Ray to cope damage. Naturally, I have unlocked plenty of nodes that increase fire damage, but a few major nodes possess these smart synergies that are really fun to unlock. Take Elemental Equilibrium by way of example, making enemies that I struck with elemental damage briefly get 25 percent resistance to those components and -50 percent immunity to other components.
How can that be helpful to me? Well, as soon as an enemy is struck by Orb of Storms, they become more immune to lightning damage but weaker to fire. And because Scorching Ray is a damage over time talent, it doesn't actually "hit" an enemy, so I never risk making them more immune to fire by accident. That's just one of a dozen small synergies my character has. I have never been a great deal of theory crafter, but seeing my build gradually come together since I unlock more major nodes was a rewarding experience.
It is slower and lacks exactly the same kinetic energy as critters ragdoll and the environment crumbles from your strikes. But what it lacks animation and action, it makes up for in spades with the strategic depth that comes from gradually molding a personality from such a robust system. I really don't feel nearly as connected to buy poe chaos orbs some of my Diablo characters since I feel like I've invested so much time to intimately understanding the way my Witch functions. She feels handcrafted even though I built her from a template. And with her passive tree almost complete and a fantastic deal of her abilities in place, she burns through packs of monsters with tremendous ferocity.