-Teachings of Dark Apostle Vrazar
Most players will have experienced this scenario: a key unit, probably holding an important objective, it's the last turn. After some poor rolling for saves in the shooting phase, the unit fails its leadership test and runs away, denying you the points, and victory. You rage internally, but knowing there were ways around it.
High Leadership characters
This is by far the easiest method of reducing the risk of failed leadership tests. Since you use the highest leadership model in the unit to take the test, it's great to have a HQ unit attached, since most have a leadership of nine or 10. IF it's fearless: even better, since the fearless rule will apply to the whole unit
AOE high leadership characters
|My 'Lord Commissar' surveying the forces|
Now this are far more specialist option, and covers units like the Lord Commissar and Dark Apostle. The idea behind these is that they grant their leadership to nearby units, potentially meaning a number of squads benefit from higher leadership. It would require some careful close positioning if you want to get the full benefit, which of course makes you more vulnerable to blast weaponry.
Whilst big units will not solve the issue of leadership values (except with Orks), it helps in another way. to be forced to take a leadership, you need to kill 25% of the unit's models (e.g. 3 our of twelve models). Therefore, a much larger unit will need to loose more models to meet the 25% quota.
A simple but relatively effective tactic. By keeping units in cover, you are increasing their defences, reducing their chance of being killed. However, do watch out for flamers if you don't have a good armour save.