Despite the growing popularity of data videos, guidance on designing narrative climaxes that maximise viewers' emotional engagement remains scarce. To address this gap, our work leverages emotional theory to derive patterns for crafting emotionally resonant climaxes of data videos. We first analyzed the climaxes of 96 data videos, categorizing them into eight emotional dimensions based on Plutchik's basic emotion model. Based on data analysis, we then formulated 40 patterns for creating narrative climaxes. To evaluate the patterns when applied as design hints, we conducted a user study with 48 participants, where Group A created data video climaxes using our patterns, Group B created them without our patterns, and Group C used other patterns as the baseline. Evaluations by two experts and 20 general audiences revealed that the climaxes created with the patterns were more emotionally engaging. The participants also praised the clarity and practicality of the patterns.