please estimate CR adjustment of this ablity (and its name..)

[With a box]

"If it's possible, then it happens"
The laws of universe is biased to him, so he wil get best result at everything
it's an extraordinary Abilitie.
it's controler will select every dice roll around 400ft from it.
he or she may from 1 to max or the dice.
Even if he selete 1 or 20 on saving throw, it doesn't mean pumble or autosucceed.

it's not strictly "its" ablity, so it still on effect even if he is unconsciousness or helpless.

it's obviously super-broken, maybe +10?

and no, I won't let anyone ploymorph into it.

[rockdeworld]

If it were the only ability you get from a template with CR, I might give it CR +5. In other words, it might allow you to take on creatures that would normally totally destroy you, but it's still not a sure thing (because CR +5 creatures have things you can't imagine).

Edit: But it's situational, in the sense that some matchups are still unwinnable with it, and some are trivially winnable with it.

Also consider that you're shifting the game by an entire RNG - enemies need to be able to hit this creature's AC+20 (or in other words, hit on a 1) to be able to hit it with this ability. And their save DCs need to be this creature's save bonus +30 +21 for it to fail its saves 50% of the time at all, and then it'd fail 100% of the time (edit: forgot how to math). Monsters get +2 BAB per CR increase, so it'd only be +10 in the melee matchup. On the other hand, most save DCs never get to 30, much less 30 20+save bonus for an xth level creature, so it would be more than +10, but high level enemies have ways around high saves, so it's still not CR +20.

It comes down to the fact that this ability is extremely polarizing. If this creature were to face an adventuring party, the party would probably either be immune to this creature's attacks, or die. For example, if it's a basilisk, they'll die if they're not immune to gaze attacks, but they'll ignore it if they are (just drop a solid fog+cloudkill on the basilisk and be on your way). So in that respect, it shouldn't be given a CR. Just put it on an equal-CR enemy you don't want the party to defeat and be on your way.

(For an example of the other end of the spectrum, if a Tarrasque had this ability, I wouldn't care because I'd just throw a Sphere of Annihilation at it, or trap it in a Widened Forcecage - or several walls of force - and Gate in an Allip, and laugh)

[Chronos]

There's no "probably" or "50% chance" about it. Either the party will be so powerful that they are 100% guaranteed to beat it, or they'll fall short, and be 100% guaranteed to lose. Neither is any fun for anyone.

[Uncle Pine]

So basically this "template" grants the ability to always maximise your and your allies' rolls and minimise your opponents' rolls, except 1s and 20s are treated as normal rolls. Which means you can't crit, you can't hope to succeed a save that would usually blow you up and you can't spam save or die abilities aiming for a lucky 1. On the other hand, you get a boon in almost every other "normal" situation.
As it is, I'd say it's worth a +4 CR adjustment with LA -, both because it's easily abusable and because it's terribly boring as it takes away from the game one of its key aspects: rolling colourful dice without knowing if you'll win or lose.
Also, clever players can simply buy a Choose Destiny spellblade and persist Choose Destiny for the whole group while spamming chain Unluck on enemies to greatly turn the odds in their favour.

[With a box]

Should I change it to ±10 fortune bonus/penalty?

[SowZ]

How about something really penalizing, but less powerful. Like he rolls 2d20 instead of 1 and his opponents roll a d10 in place of a d20. The effect is similar, (he averages 21, the opponent averages 5.5,) but there is still a random component.

[rockdeworld]

Should I change it to ±10 fortune bonus/penalty?
That's still a swing of an entire RNG for opposed checks, and half-an-RNG for everything else. You've got the idea that you don't want to create encounters that are going to be a roflstomp one way or the other, now the question is how to go about it.

+/-10 is reasonable for high optimization levels, high levels, or if the creature in question is an otherwise equal challenge* with -10 to hit on everything. In the latter case, that would make it into a boss fight, since the party would need to scrounge together an additional +10 to hit beyond what they normally need. That's reasonable if they know how to start charging/tripping/flanking/surprising all at the same time. The average group below level 10 will just fail.

+10 by itself is perfectly reasonable for high levels with maybe CR+4 adjustment.
-10 is different, because it basically means "prepare to fail everything". Mind Fog (http://www.d20srd.org/srd/spells/mindFog.htm) is a situational "save or lose suck," and this removes the "situational" and "save" parts.

*notice I didn't use "equal CR" there. CR is not reliable, so I'm trusting you know what an equal challenge for your party is.