How to play: Falstad is an extremely good ganker and his strength lies in taking out a single hero. Positioning is key on Falstad. He's good at staying at a range but his kill potential lies in being right up in the enemy's face. Know when to hang back and harass with Hammerang and when to get in there and blow your load on them. Here's how I apply his skills in battle:

Hammerang: Fantastic for harassing and pushing the lanes. This is my bread and butter skill when I play him. The slow is powerful and allows you to chase well along with Barrel Roll. I always upgrade with the ability that allows it to explode upon a second activation and that allows you to stun people that are slowed by it. If you time the explosion well you can harass really well at range and push creeps hard.

Lightening Rod: I only use this when in team fights or when I'm trying to kill someone. Never use it on creeps or to harass. It's good damage, but it's your other skills that really make the hero work. This just allows you to pump out a little extra. Don't forget to use Hammerang to slow and Barrel Roll to keep them in the AOE.

Barrel Roll: Useful for initiation AND escapes. Don't forget the latter. When initiating use barrel roll after your abilities to allow you to stay in there a little longer and get your max damage in. If you don't need to use it don't. Save it if you need to escape. Picking up the 2 charges on this is situational. If you're getting killed a lot or having trouble keeping up then get it. If not, get something more useful.

Hinterland Blast: I ALWAYS get this over Mighty Gust. The damage is fantastic and this is the skill that allows him to go from nuker to true assassin. A good Hinterland Blast is the one that's fired into the enemy's back. Use this to kill fleeing targets, after all, they're fleeing to avoid more damage and you have a way to reach them with one of the best nukes in the game. I typically avoid starting team fights with this and avoid using it for more damage in team fights. Save this for when the enemy is low and you will be rewarded.

So here's the combo:

Mount in from across the map and lock on with your Lightening Rod. Then slow them and burst them again with your Hammerang. At this point they should be stunned and still taking a lot of damage. Make sure to keep up with Barrel Roll and keep right-clicking. When you can't attack any more, and if they haven't died yet. Zap'em with Hinterland Blast and enjoy your delicious kill :) If you're in a team fight just pick on target and make them your best friend.

I hope this was helpful. I love Falstad and he always just cam naturally to me. It's surprising to hear that most people struggle with him but hopefully that will no longer be the case for you :)