Incubation Druidramp$1.03A low-cost mana creature that accelerates you into bigger spells, similar to how Dragonlord's Servant reduces the effective cost of your threats. It is not dragon-specific, but it fills the same early-game setup role.
Sarkhan's Unsealingutility$0.74This isn't cost reduction, but it rewards casting large creatures and specifically plays well in dragon-heavy decks. It serves as a powerful support piece for a dragon strategy in the same color.
Dragonspeaker Shamanramp$2.28This is the closest functional analogue: it directly reduces the cost of Dragon spells by {2} instead of {1}. It is a strict upgrade in the same role, though at a higher mana value.
Goblin Anarchomancerramp$0.32A 2-mana cost reducer for spells that share a color with it, which can function as generic spell discount in red-based multicolor decks. It is broader than Dragonlord's Servant, though not tribal-specific.
Urza's Incubatorramp$17.46A classic tribal cost reducer that can name Dragons and reduce their generic mana costs by {2}. It is much more expensive to cast, but a stronger tribal enabler for the same deck style.
Herald's Hornramp$4.65This provides tribal cost reduction for Dragons if chosen, while also offering card advantage over time. It supports the same game plan of deploying dragon threats more efficiently.
Stonybrook Banneretramp$0.56A small tribal cost reducer for a specific creature type, serving the same early-support purpose as Dragonlord's Servant. It is not for Dragons, but it is a close template for cheap tribal acceleration.
Morophon, the Boundlessramp$6.50A universal tribal enabler that can reduce the cost of Dragon spells and many others by up to {W}{U}{B}{R}{G}. It is far more expensive, but it represents the upper end of the same function.