Start with what needs defending
Merge Animals Defence describes combining animal DNA to build an army and defend a base against waves. That premise makes the condition of the base a useful reference for a merge decision. Before combining available units, identify the threat that most recently reached or endangered it. The most visually dramatic animal is not automatically the answer to that particular problem.
Read the proposed change
Inspect any information the actual interface gives about the two inputs and the resulting animal. A larger model does not prove a larger attack range, and a familiar species does not establish a special ability. If the game states a property, compare it with the defensive need you identified. If it does not, treat the combination as an experiment with an observable result.
Observe one later wave
After the change, watch whether the same kind of threat still gets through. Keep the comparison narrow enough to describe: which unit changed, what it did, and what happened near the base. The supplied excerpt does not explain merge recipes, placement rules or upgrade costs. This approach therefore offers no optimal army list. It helps turn a laboratory-themed choice into a specific defensive question rather than a sequence of unexplained combinations.
Connect an animal combination with an observed defensive need.