Colossus talk! I'm no expert, and I use spells I like, usually visually, so it's probably not the correct way, but I've done well so far and more importantly it's been fun so
Basic - I use the spirit regen one with just 1 point, it regens 3 spirit to you and your friends, and still hits reasonably ok for a 1 point (hits for about 2k at my level). Then again I only use the basic as a filler when I'm out of spirit
Passives - I max out bullwark (if that is the defense and health one) because I like my tanks to be at least semi-tanky (and I have nightmares of how squishy Cyclops is) but I don't use Osmium Skin at all (assuming that is the projectile deflection one), it sounds useless to me (and I didn't go full tank as I will explain later)
Osmium Charge is amazing, and I actually considering putting points into it at one point, but I don't like putting more than 1 point into movement spells. It still 2-shots basic mobs with 1 point anyway.
For the rest, my spec is semi-tank with pets, so I max out bullwark for the semi-tankiness, I max out Wolvie and Magik with Sinister medallion and two if the raptor artifacts that give summon duration (so I only have about 6 seconds where they aren't out). For dps I use a combination of maxed titanic slam because I love death from above moves and it does great damage (someone was saying it was nerfed but mine hits for 25k+ so /shrug) and maxed out Roar, and for single target I use maxed Colossal Punch which does silly damage even with no damage passives.
The rest of the points are 1 in the spirit regen punch, maybe 1 in the taunt if I can find a spot for it on the bars, and the rest in the defense/health aura (so only about 8/9 points in it, like I said, semi tanky)
And that's my Colossus