Know each candidate’s level and watch whether enemies are getting through.
Find a matching level
Separate the board by displayed tower level. Two different levels do not satisfy the same-level merge rule, even if the towers look similar.
The checker on this site helps identify matching levels among starting-level towers. It does not calculate which tower type will appear or how much damage the new board will deal.
- Count towers at level 1, level 2 and level 3.
- Use the checker to find levels with another matching tower.
- Inspect the actual towers at that level before deciding.
Watch the current wave first
A change can be difficult to judge while enemies are already getting through. Identify the part of the route that is causing trouble and which towers are currently handling it.
The game’s random combinations make observation useful: look at how the board behaves instead of assuming that a higher displayed level settles every decision.
- Check whether the current defense is holding.
- Notice which towers are covering the problem part of the wave.
- Make a deliberate change and watch the result.
After the merge, take a new inventory
The merged result reaches the next level, so the old count of matching towers is no longer your current board. Recount before planning another merge.
Change one thing at a time when learning the game. That gives you a clearer connection between a board change and the next wave’s behavior.
Questions before your next run
Does a legal merge guarantee a better defense?
The same-level rule makes it a valid candidate. Assess the actual tower combination and current wave before deciding whether to change the board.