How to combo gems

Ah, gem combination. So, first off, there's two types of Gems you socket in your gear:
Skill gems - These grant skills you cast. Fireball, in this case.
Support gems - Support gems don't do anything on their own, but modify any linked skill if applicable. You saw the Lesser Multiple Projectiles gem there.

Every skill has tags at the top of the description that lists what 'type' of skill it is. Here's Fireball:


Fireball has the Fire, Projectile, Spell, AoE tags. A support gem that applies to Projectile skills will link to Fireball. If you have a support gem that increases AoE radius, it will link.

Ice Arrow is also a Projectile skill, so the Lesser Multiple Projectiles gem will link to it, and you will fire multiple Ice Shots per cast.


As for how linking skill gems work, we'll take this Brass Spirit Shield as an example.

There are three sockets, but only two of these sockets are linked; the two on the right.
The support gem in the upper right is only linked to the Clarity gem below it. Frost Wall, on the left, does not benefit.

Of course, since Clarity doesn't actually hit anything, it cannot Critical either. The support gem does not apply to Clarity for that reason, since it increases Critical Strike Damage.



As for why I have these gems the way I do? I have no idea. I think I wanted to link Crit Damage to a different spell but didn't have the proper socket layout yet? Something like that.