Q: After the Howlers have done their Howl, can they charge a target they cannot see?

A: No. The Pack Master must be able to draw a clear LOS, with no intervening terrain or units, at the target when they issue the howl. Note: this LOS is for the purposes of a charge, so the Howlers could target an enemy through the Ice Witch Blizzard.

If the target of the howl flees and this takes them out of line of sight of the Howlers (i.e. because they fled behind terrain), then the Howlers will Charge to the last location where they could be seen.

Snowbeast and Summoning Horn:

Q: The Wendigo playtest rules say:
* Summoning Horn [...] Point Cost: 150
* Snowbeast Profile [...] PV: 150* [...] * Cost requires the purchase of a Shaman and Summoning Horn

So what is the cost for a Snowbeast in a warband -- 150 points or 300 points?

A: The Snowbeast has a Point Value of 150, but the Point Cost is covered by purchasing the Summoning Horn for 150 points.

Thus, if a scenario objective is dependent on having the highest point value of figures at a location, the Shaman and Horn would only count as the PV of the Shaman himself; the Snowbeast would have to be present to include those extra 150 points in the total.