When playing Ledros by sacrificing Ekko to reduce its cost, does Ekko's Deathknell ability (readying runes) trigger before or after paying the remaining cost for Ledros?

Ruling: You pay the full cost (including sacrificing Ekko) and play Ledros, then Ekko's Deathknell triggers and readies your runes.

Sequence:

• Pay 7 energy and 3 power
• Sacrifice Ekko as part of the cost
• Ledros is played
• Ekko's Deathknell triggers and readies runes