edhseer Commander synergy, explained
Land
As this land enters, you may reveal a Dragon card from your hand. This land enters tapped unless you revealed a Dragon card this way or you control a Dragon.
As this land enters, choose a color.
Add one mana of the chosen color.
activated {T} — adds 1 mana
Causes: nothing.
Cares about: nothing.
a land enters the battlefield — 1,560 cards in the game can cause this (Temple of the Dragon Queen is one).
When Temple of the Dragon Queen enters:
199 other cards care about it too. These are the ones with the most connections.