Forced concede because opponent took too long
Opponent was playing the scurry oak infinite life gain tokens combo and repeated it 170 times. While waiting there was nothing I could do, no instant response I could play. While waiting for the opponent to do their thing, waiting to draw a board wipe, I got a warning "You haven't acted recently. Act soon or you'll concede the game" although there was nothing I could do. When my opponent finally timed out and finished their turn, right when my turn started the game conceded for me, even though I could have drawn my board wipe. There is no reason I should be forced to concede when there was nothing I could do because opponent put too many triggers on the stack.

-
Rugbyman253#02939 commented
I had platinum angel out and because of too many stack abilities on other player it conceded for me even tho I was about to win the game
-
Cinnunen#38200 commented
Had the same issue, but I had cast Book of Exalted Deeds, sacrificed it and given my Resplendent angel the Enlightened -counter which says "You can't lose the game and your opponents can't win the game."
The opponents Scurry oak/life gain -combo took for ages and suddenly there was the "Act soon or you'll concede the game" -banner. Could do nothing.
I was first chuckling at "your squirrels won't help you a bit", but was forced to concede. What an anticlimax ...
Why was I penalized for simply waiting for the other guys combo to finish?
-
Algidknight#52816 commented
I had a similar issue, I had a sould warden and heliod/cleric class in play, but nothing that would create an infinite or near-infinite combo by itself.
-The opponent played anointed procession + mythos of illuna to get 3 anointed processions.
-After this they played mythos of illuna to create 8 soul wardens.
-They then played reverent hoplite with 14 devotion. This created 114 soldier tokens causing over 1000 triggers, a few hundred of them were my soul wardens which in turn triggered heliod/cleric class. The timer ran out while I was choosing targets and the game forced me to concede because, as stated by OP, "You haven't acted recently. Act soon or you'll concede the game"I was penalized in a game that I would have won if triggers were allowed to resolve normally. This was a ranked match so I'm very upset that I was forced to lose a game that I likely would have won. Especially with the token limit of 250.