I've already announced that I'm daggering him, but Geoffroy hasn't announced an action yet. He could use his action to Help or Shove, Lia would do the other. Multiple Helpers doesn't tack on any extra advantage as the rules are written. Dungeon Master could rule otherwise of course .
Since I have higher initiative I'll start and help Thomas. That way you can shove with advantage. If you wish to do something different Lia will just be struggling with him. My post was edited to reflect this Daishain. If you don't wish me to since I already rolled and missed that is fine. I'm not worried about the miss because the spell lasts for a minute. I just want the intruder gone so we aren't stuck in the tower and surrounded.
Edited: Kyrroeth on 5th Mar, 2017 - 10:37pm
Nice! I realized as I was drifting off to sleep last night that not only did I need to roll the second die for my critical hit, but I wanted people to make sure if the guy fell he fell inside, where Cratol, Onwen and Targul remain, as well as a few of Onthar's men. We didn't not want him falling where he could be healed/revived. I was going to point out if we killed him quickly enough we could loot the body before the barricade gave way. We still can, too.