How to Handle Red/Yellow Secured Dice
Players have access to the Red 'Wild' Die and need not play anything.

From the Elder Sign revised rules (page 12, Adding Dice to the Dice Pool)


  Unique Item cards often show a red die icon. During his turn, a player may discard one of these items to add the red die to his dice pool.** [...] A die that is added to the dice pool stays in the pool until the player either uses it to complete a task or discards it after a failed roll. Unless dice are locked or secured by a spell, the player returns any dice granted by common or unique items to the supply at the end of the Resolution phase.


and (page 13, Securing Dice with Spells)


  Many spells allow a player to secure a die result for later use. These are signified by the securing icon. [...] When a die is secured on a Spell card, it remains there until any player chooses to use it to complete a task, removes it from the spell to roll it (see “Removing Secured Dice” on page 14), or until another effect locks that die (see “Locked Dice” on page 12). [...]


the breakout box on (page 14, Removing Secured Dice)


  Dice secured by focusing or assisting can only be removed by the player who secured them, and they return to the dice pool at the end of his Resolution phase. Dice secured by a spell can be removed from the spell by any player during his turn for use in a roll.


From the Elder Sign FAQ


  Spells and Held Dice
  
  Spells that secure dice are cast after a player’s roll, not before. The player looks at the roll results. Then, if he wishes to secure a particular die, casts the spell and places the die on the spell. The secured die remains on the spell card until a player uses it to complete a task or until it is otherwise removed (as described below).


Barring any of the reasons below, the secured die is available to complete a task. (Like your aforementioned playing a unique item)


  • Dice may have their results modified by items/abilities before being placed on a spell, but not afterwards.
  
  • Before any roll, a player may remove some or all of the dice held on spells in order to roll them.
  
  • Any spell that has no dice remaining on it is discarded.
  
  • New dice cannot be added to a spell to replace those that
  were removed from it.
  
  • If a die becomes locked while it is on a spell, the die is removed from the spell and locked. If the spell has no dice remaining on it, the spell is discarded.