This works in concert with poe currency ability gems, which slot into pieces of gear and provide your character charms and abilities to use in battle (unlike Diablo 3, that they do not have any given skills). Items will often have multiple stone slots, and at times they're linked together. When I put an ability like Orb of Storms to a slot and then join it with Curse on Hit, Flammability and Vulnerability, every moment that my Orb of Storms hits an enemy it'll also apply both of these curses to them. It's basically an extremely robust spell-crafting system.
But it's when ability gems and the tree overlap that things get very exciting. My Necromancer relies solely on Scorching Ray to deal damage. Obviously, I have unlocked lots of nodes that boost fire damage, but some big nodes possess these smart synergies that are really fun to unlock. Take Elemental Equilibrium for example, making enemies I struck with elemental damage briefly receive 25 percent resistance to all those components and -50 percent immunity to other elements.
How can that be helpful to me? Well, as soon as an enemy is hit by Orb of Storms, they become resistant to lightning damage but poorer to fire. And because Scorching Ray is really a harm over time talent, it does not really "hit" an enemy, so I never risk making them more immune to buy poe exalted orbs fire by accident. That's just one of a dozen little synergies my personality has. I have never been a great deal of concept crafter, but viewing my build slowly come together as I unlock more important nodes has been a rewarding experience.
