there isn't a 'simple terms' for it. if you have GoSpike up, and divine insight procs, you'll use the GoSpike stacks instead of the DI buff. basically you want to have two mindblast hotkeys. one that just casts mindblast, for when MB is off cooldown and you have GoSpike stacks up, and a second one that first /cancels the GoSpike stacks which you use when DI procs. it's really not worth the hassle, and you get a microscopic amount of extra dps from it (you get small dps increase from having GoSpike up for your MB's which aren't procced from DI), but if it fucks up (like you hit mindblast but get a SWP tick .1 sec before, and don't cancel your GoSpike aura) you end up losing up to 4 potential DI procs depending on your rng.
just dont use GoSpike with DI until they fix it. it's why your mindblast randomly lights up but you can't use it, and you are losing dps.
---------- Post added 2012-12-07 at 07:56 PM ----------
TOF is very good on le-shi for a non obvious reason. you can proc twist of fate from mindsearing someone at the end of hide phases, as well as at the end of each add phase. also, during hide, your mindblast will probably be on cooldown, so the benefit from having random proc cooldown resets from DI is reduced proportionately to the length of your average hide phase. if your guilds 'get away' phases last a very long time then maybe DI could win out, but in my guild we run 3 dps warriors, two rogues, three hunters, and a ret, so they usually last about 5 seconds max.
you should be able to sprint up to lei shi using glyph of mindflay buff, recast VT and mindblast while being pushed back, then use body and soul to run back and spam SWP and FDCL spikes, then mindflay again while being pushed back, then get away should be done (or halo will be up, or use a racial like darkflight or goblin boots, or whatever).