The E part reads as follows; E: If this attack deals damage, your next control check to play an attack as a Reversal gets +X. X equals the damage dealt. How exactly does this work, since Oni Muso is not a reversal, when ever will you be able to play a reversal during your attack? What exactly am I missing here?

Thanks in advance

the effect floats on your opponent's turn so you can use it then. I love that card.

are you sure because i thought that effects ended at the end of the turn? unless stated otherwise

The tournament rules specifically state as follows:

400.6 Effects from abilities will last till the end of the turn they are played unless otherwise stated.

Because there is no a specificed end time on Oni Muso's E, that means that the effect will end at the end of the turn from which it was played.

That being said... If you could find a way to benefit from playing non-reversals on your opponents turn

Some possible cards that you would use to make that possible:

.Abyss.
.Alba.
.Charlie..
..Lizardman...
...Sakura...

Payback
Raise the Shield
Slide
Son of Arroyo**

**Some Assembly Required.

If you play Oni Muso, your opponent half blocks and takes 2 damage, then reverses you, you can block their reversal and play a reversal against them with +2 to the check. So it's totally usable in your own turn, just probably won't happen a lot.

fact is i just use oni muso for its saucy action side

When all else fails: