Fortune Thief
and
Ali from Cairo
really can't be used. Arabian Nights was top-down, and when talking about the color pie, if you cite the Time Spiral block, a general rule is Planar Chaos > Time Spiral > Future Sight.
Form of the Dragon
is flavor, and basically
Worldfire
is
supposed to be a Johnny version of "Flip a coin. The winner wins the game.", usually by some
Oblivion Ring
/
Blisterstick Shaman
combo.
Setting life totals has been
white
and
green
.
Black
has more recently used this mechanic too.
The mantle is the interesting part. I've always said white should have creature steal, flavored as indoctrination.

tortures you (without actually "torturing you" under its own, ah, tortured definition) until you denounce the evil that is


, or infiltrate your own side,
Manchurian Candidate-style.
In command zone sets, white gets "teammate" effects and inherently political mechanics like join forces.
White's removal, besides stealing, is basically temporary, has a "nonwhite" (often "black or red") requirement, or is
Divine Verdict
-type things.
On green, I say just give green flying. It's a creature mechanic, and bees and hummingbirds are at the very least central to the reproduction of most angiosperms.
Leaf Arrow
falls into "stupid card is stupid". You can't say green gets "the best" anti-flying, when
red
gets a strictly better card in the same Standard. You can't say green gets "the best"
creatures
when
blue
gets a strictly better card in the same Core Set at common! If you have to give green removal, the two options are fight and
Drop of Honey
-like effects. (You could move -X/-X, flavored still as plague, to green, but that's just splitting hairs.)
Hurricane
is close to green, honestly, but not for the "each creature with flying" as much as the "deals X damage to each creature".
White can also get sweepers in any permanent type and
Balance
-like effects, but the latter only affect one advantage at a time, to avoid why Balance is so bonkers.
Green also gets any form of ramp it wants, and can steal lands, but no other permanent type. Also,
Disciple of the Vault
-type effects that trigger whenever an opponent's artifact is destroyed.
An aside: I want green to have lifelink more than white. White can get it at uncommon, but green should get it at common, flavored as packs of predators (wolves, lions, pygmy chimpanzees) sharing game. (Black gets it at common, flavored as sadism.)
Green should
not get positive, linear artifact interaction. This includes golem/myr/construct tribal,
Tempered Steel
-like effects, artifact counting, etc. Green does get affinity, but only for creatures, green enchantments, forests (and other basic land types in a multicolor set, and even a domain form à la
Draco
), and the graveyard.
Interestingly, I disagree with MaRo about change. Retroviruses are very green; they don't think and basically just reproduce. They also mutate so rapidly that they overwhelm your immune system.
On red, I say just give us better land destruction. Seriously.
Craterize
is stupid because
Demolish
exists, and was LD really ripping up Standard in recent history? Other red effects might include
copying instants and sorceries
and
creatures but only temporarily
. The downside of "sacrifice at EOT" is clearly red. I might also suggest self-mill (and only
self-mill), to be used with

reanimation effects! Red can also get blinking and bouncing of
opponent's creatures.
Red should also, like white, benefit from being behind in some way. This is more because of red's masochistic streak.
Black can get paying life for mana, but here's the trick: It can't be
all life possible
. Black can also sacrifice creatures for mana, and again, this should be limited by tapping or sacrificing the mana source.
Blue can synergize with artifacts in any way it wants.
I'll have more later.