Even though you won't need to run fast during defiance, running fast in training will help with your efficiency. That is, it'll help you develop a better running style.
Workout;
15min warm-up
3x 5min @ zone 4 with 2min jog between
15min cool down

10min warm-up
1min hard, 1min easy
2min hard, 1min easy
3min hard, 1min easy
4min hard, 1min easy
3min hard, 1min easy
2min hard, 1min easy
1min hard, 1min easy
10min cool down

Most runners from professionals to amateurs run too fast in training. A great way to ensure you are training your aerobic system is to use a heart rate monitor.
You can use this simple equation to workout your training heart rate.
180 - age
Example: if you are 40y/o your training heart rate will be 140bpm (180 - 40 = 140).
Plus and minus 5 from your number and use that as your training zone.
Using the 140bpm example your training zone will be 135 - 145bpm.

Running after cycling or mountain biking is completely different to running by itself.
With 16 weeks still to go, now is a good time to start getting use to the feeling of running off the bike.
Ride (road or MTB) 1-2hrs
Run 30-60min

After allowing for a 10-15 min warm warm-up focus on staying inside your aerobic heart rate zone.

Workout;
15min warm-up
3x 5min @ zone 4 with 2min jog between
15min cool down

10min warm-up
1min hard, 1min easy
2min hard, 1min easy
3min hard, 1min easy
4min hard, 1min easy
3min hard, 1min easy
2min hard, 1min easy
1min hard, 1min easy
10min cool down