Merge a Nuke cash should be spent on the bottleneck that improves your current goal: spawn tier for stronger pieces, spawn speed for flow, max spawn for space, or defense when raids slow progress.
Cash is a decision tool
Merge a Nuke cash is not the goal by itself. It is the resource that lets you fix the next bottleneck. A player with slow spawns, weak pieces, crowded board space, and raid losses should not spend the same way.
Spending order
Start by naming the problem. If you need better pieces, spawn tier helps. If you need more pieces, spawn speed helps. If the board is clogged, max spawn or automation may help. If you keep losing value, defense may be the right cash move.
Cash from codes
Current codes can jump-start the early route, but code rewards should still follow the same spending logic. A reward used on the wrong bottleneck can disappear without changing your progress much.
Track results
After a big spend, watch whether income, merge speed, or safety actually improved. That feedback makes the next Merge a Nuke cash decision easier.