­Lim-Dûl's High Guard + Cannon Galleon

Fairly simple black creature; 2/1 first strike regenerate, for 3.

And a red vehicle, that turns a pair of creatures into Pirate Ships; but can be destroyed by being directly attacked (like a planeswalker).

Ok, how about something nicely aggressive but that also wants to stay back and defend?

Ok, we'll make it fight - in your turn - instead of ping; and have it die if something hits you. So if you use it, you may lose it. But if you don't use it - you're giving up a chance to lightning bolt every turn.

Repeatable creature destruction? Even with a downside this is pushed - upcost it slightly, and make it uncommon. Maybe even rare?

I... fear you're running into the "fight isn't combat damage" problem again. This will die the moment it fights anything with more than 0 power.

Oh for... seriously? First strike doesn't work in a fight?

Gah!

Fight is precisely identical to saying "Each creature deals damage equal to its power to the other". The only abilities that affect the outcome of fight are those that affect damage dealing (lifelink, deathtouch, wither, infect) or damage receiving (protection, indestructible).