Rocket Launcher

The continuous-control clause is doing the real design work here. The set was figuring out, in real time, what an artifact was allowed to do, and the rule that you must have controlled this since the beginning of your most recent turn was the brake the developers reached for when they wanted a pingable damage source that could not also be a fresh combo piece. You cannot drop it and start firing the same turn; you cannot blink or bounce it to dodge a problem without resetting the continuous-control clock and locking the gun for a turn. (Regeneration, notably, would not reset that clock, since the permanent never actually leaves the battlefield.) The self-destruct is the second brake, and it is wired into the activated ability rather than left as an independent trigger: nothing happens if the launcher just sits there, but the moment you pull the trigger, the effect schedules its own destruction at the next end step. Each cycle of firing costs you the source that produced it. That cost buys you flexibility within the turn, though: there is no tap symbol, so with enough mana you can fire it several times before it goes down. What looks like a clunky two-mana ping is the era's habit of writing activation restrictions directly into an artifact's text box to head off the abuse vectors the rest of the set was opening up. It survives now mostly as a museum piece, showing the seams of how the rules were being built.