We're running Dragon Heist and having a quite dramatic encounter where a very important & powerful villain is trying to escape the sewers with 1 hp left.
The villain became invisible as the most logical first move and started to quietly go away towards the room's exit. The party screwed up a bit and didn't prepare ANY spells for invisibility detection, despite being at 6th lvl, not even the Faerie Fire. So the DM decided that it should be quite challenging for the party to stop that invisible villain from running away, without those spells.
But it turned out that the party wanted that guy dead SO MUCH, so they came up with an interesting move: summon 8 wolves with Conjure Animals and basically try to find the invisible enemy by bumping into it. The party literally spent some time drawing lots of "projectiles" in Roll20, trying to cover every square of the room with these "wolf ramming lines":
The DM decided that the villain, being a 17 lvl boss ranger, is not stupid and he will be trying to dodge the wolves by throwing a DC 15 acrobatics skill check. If succeeded, the wolves will not notice anyone on their way. And so the wolves missed because the villain had +8 to Acrobatics.
This actually made the party even more dedicated to kill that guy so the wolves started "dashing back and forth" through the room to maximize the number of potential acrobatics checks... They ended up killing the guy and may I say that was an extremely satisfying moment for the party :).
On the other hand, some of the players felt that DM was "giving the villain a plot armor" with this acrobatics checks ruling. They argued that this should be done differently via a Ready Action ("I jump away if a wolf tries to ram me"), or by wasting the action on Dodge, or with the DEX save, not the ability check...
Here are my questions:
According to the rules, is it really possible to do the "mass ramming" of an invisible enemy with a pack of wolves?
If this tactic is reasonable, what does the villain must do to counter it? Was the acrobatics check the most reasonable choice? Shouldn't it really be the Dodge action, or the Ready action, or the DEX save?