[This post was deleted after a self-destructive wave I did on my own posts. The following is my attempt to reiterate what I said before.]
To me, this is a 100 point piece, because it's most effective in groups of 4. Let's assume a standard 18 defense, so it needs to hit an 8. It's got a built-in kind-of PC if you roll 6 or 7, which are pretty likely. Getting that with 3 damage & range is quite reasonable for a 25 point piece. Now let's add in the Enhancement you get from a full wave of 4. Now this 25 point piece has a roughly 50/50 chance of hitting for 6 damage! Suddenly that seems like a pretty efficient use of your points.
The Sacrifice Swarm can be incredibly useful if you manage to pull it off, since it does trigger on adjacent characters only. If you do manage to get opportunities, then they get the ability to make that same attack with all those benefits for free. You can easily make this work for you by anything that makes tokens and pushing them to death. If you want to stay in theme, you can go with either the first or third Rat King. I don't know if I'd be willing to break theme to make it work, since getting that initiative bonus for the map you want can be crucial, but it's worth considering for how much deadlier that makes these guys.

4x Foot Elite (Boomerang)
4x Foot Elite (Axe)
Shredder + Illusion spawning
Definitely not the best 300 points you can make, but a very fun & threatening team.

This piece seems amazing for the 25 point cost. 10/3 on a bargain cheap piece with side step for positioning AND enhancement AND free range attacks when allies die?

He’s so good. 3 of these little guys with the Foot Elite Dynamite is effective to say the least.

The option to make ranged attacks makes these figures a little better than the 25-point Elite Axes (yay Opportunity tokens!) but on pure Foot Clan forces most of the damage output will probably be from close combat. I think the Boomerang attack power is the best of the Elite special powers. Do not discount the fact that at 25-points this dial (like all the TMNT4 Elites) has some of the best Attack/Damage values of Foot Clan generics, such that even if these figures end up making only close attacks, they still are capable of dealing damage through (most) damage reducers.