Just before the basilisk uses it's ranged poison attack it will coil up. You can see the green reflection on your character from incoming poison attacks letting you know to change directions when running away. It's best to be on a fast mount because a hit from the venom ball will do direct damage to players even on mounts.
This thing is a titanaboa on steroids, if you see it’s tail popping out of the ground, try not to get near it unless you have a few strong fighters. If the gas ball hits your tame, get out of the cloud of poison it will probably kill you, except if you have a hazmat suit on.
Tame a high level megalosaurus and wear hazmat at all time just in case. Abb megalosaurus can rip through anything. Just avoid its first venom ball them get all up in its face. Haven’t encountered a 150 yet but seem to have no issue this way.
Strangely enough, this thing was at portal spawn. Completely wiped out our parasaur mounts and raptor army with ease. However, our 4 bulb dogs manage to make their way into a glitch spot under his belly and take it out untouched!!
Tranquilizing bite. To get an easy kill with any single large creature, shoot it from a safe distance to agro it to you.Then send some tamed raptors, sarcos, carnos, etc to kill it. I do this while on a Paracer using its knockback to keep large enemies at a safe distance. Works wonders with spinos and crabs on Aberration.
If you are on foot, ignore them. They have good HP and spit poison; If you plan to take it down with a mount, use Hazmat Suit Hats or be ready to pump yourself Medical Brews, also backpedal to minimize the damage done to your headgear.