Card Spotlight
A six-mana 6/6 flying Dragon that creates a 5/5 flying Dragon token whenever another nontoken Dragon you control enters. For {1}{R}, your Dragons get +1/+0 until end of turn.
Commander Spotlight
Lathliss, Dragon Queen ↗
A six-mana 6/6 flying Dragon that creates a 5/5 flying Dragon token whenever another nontoken Dragon you control enters. For {1}{R}, your Dragons get +1/+0 until end of turn.
See Lathliss, Dragon Queen's full stats and printings →
As the commander of Reign of Dragons she turns each Dragon spell into two fliers, and the deck's ramp exists to get her and the Dragons out early. Her weakness is the deck's weakness: almost no protection and little card draw, so removal on Lathliss or one board wipe often decides the game.
She belongs in red Dragon decks led by another commander, where she adds a 5/5 to every Dragon cast after her. Outside a Dragon-heavy list she is a six-mana 6/6 flier with a pump ability, which red has better options for.
Dragon Tempest ↗
Each Dragon that enters deals damage equal to your Dragon count, and Lathliss's token is a second Dragon entering.
Scourge of Valkas ↗
The same Dragon-enters damage on a Dragon body, which also triggers Lathliss when it is cast.
Dragonspeaker Shaman ↗
Takes {2} off every Dragon spell, including Lathliss when you cast her from the command zone.
Terror of the Peaks ↗
Deals damage equal to an entering creature's power, so each 5/5 token Lathliss makes is also 5 damage to any target.
Lathliss is inexpensive. She was first printed in Core Set 2019 and reprinted several times since, including Foundations and now Reign of Dragons. The precon includes most of the Dragon support listed here, which makes it a cheaper starting point than collecting the singles.
No. She triggers only on nontoken Dragons, so each Dragon you cast makes one 5/5 token. The token is still a Dragon entering, though, so it triggers cards like Dragon Tempest and Scourge of Valkas a second time.
For a Dragon deck, yes. Every Dragon you cast arrives with a 5/5 flier attached, which roughly doubles the board the deck builds. The cost is that she is six mana and the 99 has little protection, so the deck depends on keeping her alive once she lands.
The deck runs several cards that make Dragon spells cheaper or produce mana only for Dragons, starting with Dragonspeaker Shaman, which takes {2} off every Dragon spell. With those out, Dragons start landing around turn four instead of turn six.