Yusri's Flip Side (EDH / Commander)

The odds to get Omniscience state with Yusri are about 3% (every coin flip is independant and identically distributed, following a Bernoulli variable of parameter 0.5), but when you include Krark's Thumb the odds of winning a coin flip become 1 minus the odds of losing two, so 3/4, or 75%, so getting Omniscience has odds 23% now.

But things start to get interesting when you are able to clone either Yusri or the Thumb, the latter being more benefitting, sadly it is easier to clone a legendary creature than a legendary artifact.
Fortunately there are other ways to achieve this goal, with say Strionic Resonator ; Tawnos, Urza's Apprentice and even Lithoform Engine you can copy a triggered ability, may it be Yusri's or Krark's Thumb's, although this strategy is beyond risky, having either to pay a lot of mana for the thumb, or a lot of life for Yusri to succeed.

Note that although having multiple copies of Yusri does not necessarily help the odds too much (merely doubling them roughly), having multiple copies of Krark's Thumb stack the coin flip replacement effects, so with two thumbs you will be flipping 4 coins instead of 1, making the odds of achieving Omniscience a whopping 72% (more than triple the odds with one thumb).

The strategy to mastering Yusri then becomes either not being able to lose too much life and gambling with Yusri multiple times, or having a lot of thumbs in play.

WARNING : this is a mid-budget deck list, some cards I have included can be easily replaced with other much cheaper cards, these include mostly lands and Urza's Saga.