Go here for the complete article. But if you want to know what’s important, look no further:

Thought you were being clever and saved your Founder coins for the Survive the Storm event?
For every 100 unspent Founder’s Coins still in possession, each player will automatically receive a Founder’s Llama, located in the Loot Tab.”

The Founder’s coin CURRENCY have been replaced with Storm tickets which can be used to purchase Storm Llama’s that will have a chance (unfortunately, if you dislike RNG) to give the following rewards:
– 4 new heroes
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– hydraulic weapon schematics
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– 2 new defenders
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Storm tickets are obtained by playing the Survive the Storm mode and surviving Mutant Storms (husk storms with modifiers for husks and players).

Note: This is a time sensitive event, so eventually the event will end and you will not be able to get these specific rewards.