I did a small breakdown of the Letters to the Dead event, looking over the roadmap costs and is worthwhile doing etc.
Total Energy Cost per day: 128
Event Reward: 100 Tokens (1 Pull)
Total Energy Cost per day: 324
Event Reward: 250 Tokens (2.5 pulls)
Total Energy Cost per day: 452
Event Reward: 350 Tokens (7 pulls every 2 days)
Assuming the roadmaps run for the full 12 days you will get 42 total pulls.
Me with 79 max energy regens over 240 natural energy per day.