It really isn't that bad of a skill to work. The biggest problem for a lot of people is that they wait until they have a nearly finished char before they start training ninjitsu. By that time they have high strength and dex and a low mana pool and little or no meditation/focus, so its DS, DS, wait for mana, DS, DS, wait for mana. If you take Lynks advice you can pretty much DS all day long if you wanted. I usually let med and focus go to GM and set intel to rise, soulstone stealth and hiding to the char when it's time to do shadowjumps, then stone those skills back off when it's time for DS. Once I get my ninjitsu where I want it, I'll work on any other skill that requires a lot of mana (chiv or bushido), and once I'm finished getting those skills where I want them, then I'll set my intel, meditation and focus to decrease and begin working on the melee skills. While you still have necro and in lich form, if your planning on having healing on the char just load up on a bunch of bandies and don't wear HP regen items and just keep healing yourself as your life drains.