When it's flying around shooting the lasers, just stay under it to avoid them. I'm pretty sure you can't hurt it when it's in the air like this anyway so don't bother shooting it now. When it stops and drives itself into the ground, make sure you're not under it and jump to avoid the shockwave. There's an extra shockwave after each time it does this so be prepared. When it's in the ground and whipping around that tentacle, just keep jumping over it while firing at it. Each time it lands in the ground it extends another tentacle to whip around and it does get harder, but if you just keep jumping in place you should get it eventually. It's really not that bad a boss.