I found that Xnolphod can make your slow dark in attack team able to charge in 9 tile from calculation.
Warning : This calculation have something wrong
You can make your Xnolphod charge in 9 tile with mana level 23 troop (+13% mana) or level 11 (+9% mana) if he is at +20.
Let say you put level 5 mana troop (+7% mana) on your dark slow hero+0. If your match 9 tile, he will get 9*1.07=9.63 tile and 9.63/12 = 80.25%. That mean when you use Xnolphod skill that add 20% mana. Your dark slow will charge.
And if you have x2 Xnolphod, you can make Alfrike or Boss Wolf charge within 9 tile even you don’t put any mana troop or emblem on Alfrike or Boss Wolf. (9/13.5=66.67% , 66.67% + 20% + 20% = 106.67%)
This correct calculation is here