Nested Blue is a Basic Blooncard in Bloons Card Storm. It spawns a Red Bloon if it is destroyed, which does not inherit any modified properties of its parent (e.g. its Delay or being On Fire). Leaking a Nested Blue will not decrease delay of its summoned Bloon. It can be summoned by the Nested Green, which itself can be summoned by a Nested Yellow.
Nested Blues have the same cost and HP as normal Blue Bloons except have only 1 charge, 1 delay, but can spawn extra bloons. However, the total HP from a Nested Blue card is less than a normal Blue Bloon (90 HP instead of 120 HP), and its total delay with the red bloon is 4, which is significantly higher than any other 1 or 2 cost bloon.
The extra Red Bloon inside forces the opponent to use low damage attackers like Alchemist Monkey instead of high ATK burst ones like Sniper Monkey.
Compared to the other Nested Bloons, playing a Nested Blue is easier early on due to cost, and is a decent choice for that. It can synergize with cards that affect all bloons on board like Bloon Embiggen because it will stay on board for longer, or cards that trigger when a Bloon is played like Bolstered Bloon or Ceramic Glazing Klin.
Nested Blue also exists within Nested Green and Nested Yellow cards, however those cards are extremly weak.
It is possible to use Quincy's minor ability Arrow Shot to pop the Nested Bloons when they are about to leak with very low health to make its next bloon faster, however that is not recomended with Nested Blue.
This card is very similar to Zombie Blue Bloon, another 1 cost 1 charge 4 total delay bloon. Unlike it, Nested blue has higher on play pressure and higher total health ( 90 compared to 80 ), but it dosen't synergize with Undead Bloon synergizers like Ezili and Dart Arts Wizard.