I've been playing some 500 point games at work on a lunchtime and today I managed to squeeze a Riptide into the list (well... it was a few points over but my opponent was kind enough to let it slide!)
The reason I brought out the big guy was primarily to act as a fire-magnet for my opponents Vindicator.
I hate the Vindicator. There have been so many occasions where the release of S10 AP2 Large Blasts has resulted in the immediate demise of a huge number of my little blue men. It's especially a problem because in our lunchtime battles, our board is probably only 3 feet square. The Vindicator threat range is HUGE in this environment!
So the plan is that he shoots a pie plate at my Riptide and it takes a wound (or maybe not because of the invuln). I move closer and shoot with my Nova-charged Ion Cannon, penetrate the Vindicator and laugh. If it's still alive, shoot it some more with my Fusion Gun.
There are several issues with this plan. First of all, Nova-charge has a 33% chance of failure (and causing a wound), then there is a 16% chance of getting Hot, then there is the Scatter issue with 66% to head off-target (although if it does scatter it might still hit) and finally we need to roll to penetrate (that's a 33% chance with a re-roll) and then see if it explodes (33% again).
Not looking very likely, but pretty funny if it does. I probably have a much better chance of it assploding if I hit it at half range with the Fusion Gun.
BS3 means 50% chance to hit, with a re-roll. There is then a 72% chance of hitting enough with 2D6 to penetrate the front armour. With AP1 it's probably going to be annihilated 66% of the time because of the +2 to the damage table roll.
There is another issue with this though. An important one:
If you shoot the Nova-charged Ion Cannon, because it is Ordnance, you cannot shoot the Fusion Gun as well.
The basic rule book (p51) clearly defines:
"If a non-vehicle model fires an Ordnance weapon, then the massive recoil from the Ordnance weapon means the model cannot fire other weapons that phase."
So even though a Multi-tracker (or the Monstrous Creature rule) would allow multiple weapons to be fired (MCs rule defines 2 weapons can be fired, and a MT defines an additional weapon), it would seem than the Ordnance rule would forbid this.
There is an argument to say that the Multi-tracker rule overrides the Ordnance issue (Basic Rule Book p7):
"On rare occasions, a conflict will arise between a rule in this rulebook, and one printed in a codex. When this occurs, the rule printed in the codex always takes precedence"
But I doubt you can really, truly, get away with that and still keep a clear conscience. I like to make my opponent suffer... But I don't like to be underhanded about it.
So I'm thinking that in future, I'm much better off keeping the Nova-charge for useful items like an improved Invuln save, or Ripple-firing the Fusion Gun. And if the Vindicator survives that, I can always Assault it and Smash it's back doors in (if you'll excuse the phrase).