Easy tame - zip line, tanky ravager, handful of hazard helmets. Aggro, have line already placed at angle so you can adjust elevation above the basilisk. Jump on line near basilisk while he is biting, and inch up just until the bite barely stops reaching you. If you do this right and don’t put too much distance between you and snake he will keep biting and missing, and will not fire the gas and will stay there the entire tame while you drop eggs (FROM YOUR PERSONAL INVENTORY NOT YOUR TAME). Basically you’re staying between his two attack ranges. As long as no wild critters aggro him away you will get perfect tame. In an ideal world have a partner maintain a perimeter clear of wild dinos.
If you are looking to get a basilisk on crystal isles don’t even try without forcetame or spawn rock drakes due to the drakes not spawning. Thanks for adding acid spitting snakes on the map TAHT CANT BE TAMED