I'm unsure what to make of Spinal right now. He seems like a good character on paper, but I'm not sure how to properly play him.
I think his best use of meter will be his shadow searing skull. End combos early with it for extra damage, or extending combos after a launcher ender or carry ender. Either way, that instinct curse seems crucial to his game. Doesn't the instinct curse slowly give Spinal the instinct that drains from the opponent? Spinal being in instinct mode sounds like the gameplan to go for, and if you can expedite the process, by all means go for it.
Going back to his launcher ender, I read on Test Your Might that you can cancel the ending frames of his launcher ender into the overhead searing skull, giving you good oki. I haven't tested this yet, but I will have to do so after work today. Either way, it sounds awesome.
Spinal plays very defensive at first until you can score a knockdown for mix up and get some skulls. Some starter tips are to always know what you can absorb and what risks are there in attempting to absorb it.
Examples are Sadira's air daggers. You can absorb them, forcing her to not be able to grapple down to you, but she may still have her 2nd air jump and could still attack you with a normal. Know which situations you should absorb and which you should teleport around. Another example would be Jago or Orchid at range. You are basically safe to do absorb if you see either of them FLY across the screen. If they are mid-range, I wouldn't suggest attempting to absorb special moves because they are too close and could easily attack you normally. DO NOT ATTEMPT TO ABSORB THUNDER.
Once you have some skulls, it's time to know how to use them to mix up your opponent and create 50/50s or general guessing games. Launcher ender is a great way to end a combo and start pressure. On test your might, the guy was right about ending the launcher combo with a HP Fireball, but you should follow up that launcher ender with a MP poke cancelled into HP Fireball, simply to create space between you and the opponent for you do be able to do a HP poke safely (cancel into shoulder charge or low fireball), so the overhead fireball will land on the opponent.
Teleport crazyness is another thing that skulls lead to. When you are in instinct mode, I believe teleport spam should be your ideal movement. It will make the opponent panic and start pressing buttons, in which you do a LK teleport and poke at them with HP for a counter hit or whatnot. If possible, always keep a fireball on screen. MP fireball is +5 on block. Great for making frame traps.
As for meter usage, it's very match up dependent. Against Sadira or Thunder, Shadow Searing Skull all day off of combos and hit confirmed pokes. Thunder's instinct is a natural threat to everything Spinal. Sadira's instinct can lead to a 80% unbreakable combo (with 2 bars) , which can be devastating in your 2nd health bar. Depending how the match is going, I often use his Shadow Sword Swinging attack thing for added damage before ending a combo. I'd rather rack up 45-60% damage from a single mix up using 1-2 skulls than attempting to mix up 3-4 times each round.
Fun absorb facts: #1 You can absorb Glacius' Shatter. His unblockable will give you a Skull. You can sort of do this on reaction, but it's half prediction.
#2 If you see Sabrewulf running from mid-full screen, use Absorb and punish that puppy. Only bad Sabrewulf players do this, but take what you can get and beware of it. If you know a Sabrewulf is eager to use his uppercut on wake up, there's plenty of false meatys you can do and then use absorb.
Note: Jago can Wind Kick over LP Fireballs. Kind of ruins LP + HP fireball traps against him.
