I feel the need to clarify this a bit:
The "combo theme" could also be done within a single ability. I suggested two spells to make it easier for the contestants to come up with a proper combo. I think 4 spells should fit a hero contest better, but a focus on optimal synergy would be cool in that kind of contest aswell. As for the two spells: They should not be viewed as two seperate spells. You will effectively be making one system to support the combo.
A single spell should reinforce itself in some way; like incinerate's increasing damage and explosion. This principle could be applied to a plethora of stacking skills like increasing a chance to bash a target with each successive hit or on each cast. For active skills the spell could have two effects for example: 1. devour ground unit, 2. spit devoured unit as a missile to target air units. Or: 1: Freeze target, 2: Explode Frozen Target.
A double spell should reinforce eachothers effect. A big part of the spell making should be in designing a strategic philosophy behind the combo. Make the player focus on planning and timing to pull off the combo to it's full potential. (Chobibo, you did not specify how your spells should be related in combat, you just picked a similar theme, which is nót what I meant)
Example for a single combo spell:
Polarize v1: Causes all units within an AoE to become Plus for 90 seconds. If a unit is already Polarized, this will alternate its pole between Plus and Minus Every Minus unit creates shocks that damage nearby Plus units. In summary: Plus = Target, Minus = Source. The spell targets allies and enemies.
Philosophy:
In game the player would cast polarize on his melee units to make them plus. When these units are subsequently in battle, the player will cast the ability again, making his allies (who were already plus) become minus, and the enemies (who were nothing) become plus. Now the (minus) allies deal passive damage to the (plus) enemy.
If an enemy hero has the same ability, he can also cast Polarize again, making the enemies become minus and the allies become plus again. Now the (plus) allies receive damage from the (minus) enemies). In other words, this is also an effective counter to itself.
The AoE and double edgyness of the spell would require some skill for the player, but would also play give the satisfaction of a plan well executed.
Example of a two spell combo:
- Polarize v2: The hero causes all units in an AoE to become positively charged (Plus). This time the charge lowers movementspeed and cause spells to do increased damage. Deals 50 damage to negatively charged units (Minus) and provides a % chance to stun.
- Static: The hero zaps a target with a bolt of electricity. The bolt jumps to nearby Plus targets, giving a % chance to stun. Each target hit by the bolt becomes negatively charged (Minus). Dispells polarize.
In summary: in this example Polarize sets up spelldamage and a lightning rod so the Static spell becomes much more effective. At the same time Static sets up minus so the Polarize spell becomes more effective. Both spells could be usefull separately aswell.
=/ sry for the long post