So here is the idea:
You know all those useless gravestones that sit out by people's bases. They only give 20 elixir, ( or 1 dark Elixir) when collected, and really thats only a drop in the bucket when a player can bring in +100k on a good raid. So let's make use of them with a new attacking spell!
- What makes this unit/spell unique compared to the other units/spells in the game: What the spell would do is, when dropped on the gravestones, it would bring forth undead monsters. These monsters would be the undead "whatever", and they would then join the attacking troops against the base.
This spell would have the radius of a lightning spell, maybe slightly larger. After the spell takes effect, the gravestones would disappear as the monsters appeared, one per gravestone for small undead or multiple gravestones for a larger undead.
Spell cost could be anywhere from 500-1000 dark Elixir to start off with.
The monsters summoned would have a strength that could partially be determined by the level of the spell.
- What kind of strategies this new spell would enable (concrete examples are best) & What kind of army composition includes this spell or, how it could combine with other units for more advanced strategies:
Well if there were no gravestones to be had, the player could drop the spell on witches that they were using and the spell would double the amount of skeletons summoned for a sort period of time. And if dropped on a witch while she walked over the gravestones, then it would double her summoning ability and bring forth undead monsters. This would help in raiding as it would bring in more troops to eek out that victory star in a close loss.
- How someone could redo their base to protect against attacks from this spell: people would have to make sure that they kept their gravestones picked up.



