Lair of the Dragon Lord

Whenever Lair of the Dragon Lord or another lair enters the battlefield under your control, you may put a +1/+1 counter on target dragon you control.
Pay 1 life, {t}: Add {2} in any combination of colors. Spend this mana only to cast dragon spells or activate an ability of a dragon.
"With great power comes...my dominion."
--Tal-Sharek, the Sovereign