There will be two challenges that will be Bloons right now.
Pack Name: Hardiiho
Link:
http://www.myninjakiwi.com/pack/Bloons/481439Difficulty 1-10- 5 or 6
Length: 6 Levels
Point Value: 30 points or 5 points per level
Comments: Challenges are back with a 6 level Pack
Pack Name: Trial And Error
Link:
http://www.myninjakiwi.com/pack/Bloons/467732Difficulty: N/A
Length: 16 Levels
Point Value 40 points or 2 points per level you get done
Comments: You either need some amazing luck, or just use Trial and Error to beat this pack.
Please take the picture on the last level completed to decrease the chance of doctering the picture.