When casting a spell that affects multiple targets, such as scorching ray or eldritch blast , do I fire one ray or beam, determine the result, and fire again? Or do I have to choose all the targets before making any attack rolls?
Even though the duration of each of these spells is instantaneous, you choose the targets and resolve the attacks consecutively, not all at once. If you want, you can declare all your targets before making any attacks, but you would still roll separately for each attack (and damage, if appropriate).
Both Eldritch Blast and Scorching Ray have a phrase specifically allowing one target or several. Bones of the Earth does not specifically allow this, and in fact states you must target "spaces" (more than one) on the ground. But one of the spaces could be grown with consecutive bones.
Can you? Can you just get one wobbly 180 foot pillar consisting of six parts? Or does the pillars have to be separate? Thanks.
When players get creative.
I think you would have to have at least two bones stacks. But one of the stacks could contain all of the bones except one.
Both Eldritch Blast and Scorching Ray have a phrase specifically allowing one target or several. Bones of the Earth does not specifically allow this, and in fact states you must target "spaces" (more than one) on the ground. But one of the spaces could be grown with consecutive bones.
So you could have two 90 feet bone stacks or one 150 feet and a 30 feet but not one 180 feet stack
When players get creative.
EB and SR also both make attack rolls which have their own rules and are resolved one at a time. Bones of the earth does not.
I would argue that bones of the earth's wording allows for it to only target a single space, but not with multiple pillars.
Subsequent castings of the spell would allow you to target the existing pillars though (obviously that is more limited than what you are going for).