download whirlwind effect model on the hiveworkshop. this is basically so your leviathen thing wont have a little blademaster in the middle spinning.
1. attach the effect to the leviathan
2. play an attack animation and use a timer trigger to pause the animation so the weapon is horizontal (at impact point).
3. use a 0.04 second periodic trigger to rapidly change the facing angle of the leviathan so it looks like he is spinning.
4. viola, spinning giant fish of doom.
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory