I’m going to list just one skill each, from a bunch of games I’ve played.
Path of Exile -
Essence Drain / Contagion.
This skill combo starts out somewhat clunky and ineffective, but after investment, this skill is the pinnacle of Feel-Good. Degens with proliferation usually feel good as is, but the satisfying “whoosh” as it spreads like a plague through enemies makes this by far my favourite skill in an ARPG currently.
Diablo 3 -
I’m a huge fan of this skill, for similar reasons to ED Contagion. Instead of being focused on wide-spread plague shenanigans, this skill being more of a Few-Target, stackable dot that spreads on kill is a nice balance of “Keep casting for more damage” or “Cast a few times and hope it’s enough to kill and spread the haunts”.
Dota 2 -
False Promise (Oracle)
Usually this skill delays all damage and healing for the duration of the buff, with healing during the buff being doubled. I feel a variant of this skill could be extremely interesting as both an offensive and defensive option in Last Epoch. Being able to cast it on enemies OR allies, alongside being paired with a full skill tree would make this skill have incredible versatility, and useful in scenarios where you would be rewarded for not immediately shredding through everything. An example could be casting this skill as an AoE on a bunch of mobs at a boss, dropping ice-nova on them four or five times, then positioning them to proliferate on the boss when False Promise expires for a nuke.
Grim Dawn -
Panetti’s Replicating missile
Grimdawn made magic missile feel good. Not much to say, just a really good take on a staple skill that feels satisfying to use.
This skill is a single-target nuke that hits an enemy, dealing damage equal to a third of your maximum health, the closer you are to 50% HP. Every percent above or below 50% hp, reduces the damage of the skill, scaling exponentially (At say 30%HP or 70%hp, you would deal considerably less damage). It’s found on a class which usually has extremely high HP values, turning it into a berserker-style nuke. It makes it feel rewarding to be tanky, and confident enough to manage your HP well.
Tree of Saviour-
Joint Penalty/Physical Link (Linker)
These skill sets up a “Link” between enemies / allies respectively, spreading any damage taken by one target, to all enemies/allies they are linked to. This is a cool and somewhat unique support skill that would enable some single-target builds, and is a great skill for party play.