Challenge #1: Energy Resistance
|Is that fire damage? Oh... that's too bad...|
There is nothing that is a bigger pain in the rear than charging up your big gun, only to find that the enemy is going to knock between 5 and 10 points off your damage. Or, worse, that your enemy is immune to that magic because of the element you've chosen to use. This is the most obvious pitfall out there, and a lot of players are rolling their eyes reading this, but I've seen this scuttle blasters' effectiveness more than once with players who go all-in on a given element, and then find by mid-level that they're essentially casting with one hand tied behind their back.
Challenge #2: Evasion and High Saves
|Did you just throw a fireball at me, you pleb?|
Area of effect spells have the same satisfaction you get from dropping a sledgehammer on a problem. And when they work, hoo boy do they work... but when they whiff it can take all the wind out of your sails.
Challenge #3: Spell Resistance
|Fool! You have no power here.|
Spell resistance is the absolute bane of blaster casters. While it isn't usually an immediate issue when a campaign starts, it's going to start cropping up as soon as your campaign deals with outsiders, dragons, and other powerful monster types... so you need to be prepared for it.
Challenge #4: Sight Lines and Effective Firing
|Got you, you little bastard!|
One of the simplest ways to take away a blaster's ability to affect you is to vanish. Whether it's into a cloud of smoke, by turning invisible, or ducking behind total cover, not having a line of sight/line of effect to a target can stymie you in some of the most frustrating ways. And it's going to happen sooner or later, so you need to be prepared for it.
Challenge #5: Actually Dealing Damage
|These numbers just aren't adding up...|
One of the unfortunate truths about blaster casters is that they just don't pack the wallop you want them to... and this only gets truer as you go up in level. As such, you need to tweak your load out to make sure that you are getting every point of damage you can out of your spells.