Choice of correct design pattern for spell-casting mechanism

I'm new in OOD and I don't really know how to handle the spell-casting mechanism which i want to implement in my game.

• I want to produce following classesTeam, Actor, Spell and interface SpellEffect
• Actor can cast spells on other actors however the spell can have different behaviour while being casted on allies and enemies ( ally is an actor from the same team )

I tried this way:

• I implement SpellEffect in Damaging, Stunning, Healing classes which overrides executeOn(Actor a)
• In Spell class I have two lists of SpellEffect - one for allies and second for enemies so in the Spell class I need to know is the attacked actor is and ally or enemy of the caster

• I was thinking about StrategyPattern for spell so I can do something like this:

  actor.setCastingStrategy( new TargetingAllyStrategy() )
  
  

• Strategies would be then something like:

  execute a spell on the targeted actor using `Spells`'s `allyCast()` method
  
  

However I'm not sure about passing Actor object to the lower level object. Moreover what if not every actor can be stunned? Should I make any inherited class UnstunnableActor ? Or maybe use instanceOf to check implemented interfaces. I'm pretty new in the topic so any help would be great.