In the last three games I’ve used Skeletal Swarming, in both Zendikar Expeditions and Duets of Mana, when my skeleton tokens die, the game freezes.
This has occurred both offensively (my skeletons berserking into something) and defensively (blocking).
As soon as they take lethal damage, it freezes and I have to force-quit.
Hello @madwren,
Thank you for all the information provided, this issue will be investigated!
If you have any additional information that you consider relevant, please don’t hesitate to send me 
Rebeca.
@Oktagon_Support may be similar and related issue.
https://forums.505go.com/discussion/85618/first-strike-critical-bug-issue