Currently, there are practice dummies in the Rikti War Zone, but they have several limitations: They're locked to level 35, they have 100% resistance to all damage, they don't always spawn, and they're only in the Rikti War Zone. I would like to see improved practice dummies put into place, to better help us test our powers. These new practice dummies would:
Use the level scaling system used by giant monsters and enemies in zone events, so they would always mimic the effectiveness of even-level enemies.
Use whatever trick Ajax uses in Dean MacArthur's redside story arc to be invincible, rather than 100% damage resistance. This form of NPC invulnerability still shows damage numbers in the combat log and above the target's head, so it would let us more easily test the damage of various powers and setups.
Consistently spawn in the zone. All the other static NPCs manage it, even those new combat-enabled trainers, so the practice dummies doing it too would be great.
Be placeable in supergroup bases.
Appear in a variety of places throughout the city. The Rikti War Zone is often packed with players doing mothership raids, so being able to test powers in a place where server performance isn't so up in the air would be useful.
All together, I think this would make for a great addition to the game.