I PC shot Izka with an immobilizing shot, in effect immobilizing him for 4 rounds. The PCs easily killed the toughest villain in the campaign.

Am I missing something on how to use the card? How would you handle it? Also, an immobilized character is unable to use actions? Or he simply cannot move?

So what did the horde of beastmen around Izka do while their leader was immobilised?

To my knowledge, you can still use actions if you're immobilised.

It is not 4 rounds : at the end of the Archer round, you take off one Token, 3 left. The creature immobilized can use its action to take off one Recharge token, 2 left. Archer plays, 1 left. Creature plays, none left. So it's really 2 rounds the creature did not play.

If you want to, you can argue Izka is "Invigorated"-like (from the location, his herdstone and the storm with lightning striking all around) and takes off an extra token so he can play the 2nd round (i would not do that, he bought the card and it should be usefull). And remember Immobilizing Shot has a range of "Close" and he is not alone. he also can use ACE (well A and E) to get Defence dice while he is shot at.

My archer used it and it did save the party's life. They could finish the Gor and 1 Ungor Henchmen group that were left before taking him out. He did drop the Tank still. They were already well wounded from the rest of the herd.

Well, I failed to mention that the attack took place in Stromdorf. The heroes had stolen the stone, and Izka, together with the Foaldeath (who now hated the PCs for killing his mother twice) they sieged the village.

By the way, there was a shaman spell for foaldeath, can't remember the name, but all it did was make roots grow out of the ground. The requisites of the spell were 'swampy or marshy ground'. I assumed that the ground of the village was full of mud, therefore it was ok for the spell, but the PCs rebelled against it.

So, I guess, I am complaning because on one hand, a muddy ground cannot be used for the spell, but on the other hand, they can Imoobilize the huge wargore with a single arrow on the ground (he was prone when he got immobilized).

Don't ever let the player's tell you what you can or can't do. If you want to use the spell in a muddy town its your choice. You're the GM! This is RP not a boardgame. In the end you make the rules.

That said if you decide to change rules affecting the PC's, let them know before they use that ability so they won't feel cheated.

-L

Think of it as he was pierced and stung in the ground and has to spend action to take the arrow out, or maybe his mail shirt got pierced and stuck into the ground (you mentioned him beeing prone), he still has to take the arrow off. It is the benefit of that Close Range action

For the Foaldeath spell, it is your decision. The idea of the spell is to overgrow the (marsh/swamp) vegetation thru magic and the muddy grounds in town kinda doesnt fit i'd say. But it's not really a problem. Either way, you don't have to fight against your player as a GM (you seem frustrated), more like present them a story and challenges that they will (hopefully) enjoy, resolve / overcome.

If they did not allow you to cast that tangling roots spell, then I would not allow them the pinning shot either...
If they try to outlogic it as saying that there are not enough roots in the mud in town to base your spell off of, you can simply retort that all that mud does not exactly make a good anchor for the arrow to pin Izka to.

But personally, I would not have gone with a beastman-horde leader that runs off on his own. If he had any loyal subjects left at that point, after losing the stone, that would probably be the last of them.

I had this come up in my run of encounter (at the clearing), use of Immobilizing Shot was vital to heroes not getting massacred but was not overpowered. Reasons above, also the fact that the attempt failed first time (if there's an attack for monster to Dodge and spend an aggression die to help counter, that's it).

If needed, I would allow other monsters to use their actions to aid one held by entangling shot (it's still 1 action 1 round, you just don't see same monster spend all actions).

I would also allow a monster/npc under this to try a Perform a Stunt (Athletics) to break free (say vs 2 purple with 1 black per token on card past first, buddies can lend assistance for fortune, reflects that a high Strength creature hard to pin down).