Main phrase: “Till doomsday” → until the end of the world, endlessly.

Answer: “Forever” → without end.

Common idea: Both mean something lasting indefinitely with no conclusion.

Main phrase: “Play ducks and drakes” → to squander money or resources carelessly.

Answer: “Waste recklessly” → to use something without thought or care.

Common idea: Both emphasize careless, foolish waste of resources.