As @omenomaho says.
- Heavy can use jet pack (3AP/2WP) without fumbling (so you don’t care about putting skill points into speed)
- Heavy’s ability for level 6 is “inspire” which gives 1WP to everybody when the heavy kills an enemy
- Priest’s ability for level 7 is “mind crush” which costs 0AP/6WP which damages all enemies within 10 tiles for 100 (armor has no effect of course)
- It is not difficult to have a priest with 25/27WP by maxing his WP and choosing the correct head mutation => can do 4 consecutive mindcrush if needed
PS: regeneration uses 4AP and restores half your WP (so you get 12-13 WP back by sitting one turn with one of your priests)