Introduction
This is a 'what if' suggestion, and it assumes that a user will be able to choose their party make-up.
Having 2 or more of 1 class in your party would add 'synergies'. Having a full party of 1 class would add an additional level of 'synergy'.
Synergies are intended to make experimenting with different parties fun and effective. Of course to gain a synergy the player must sacrifice flexibility. The chance of success can be used to balance synergies, so they don't become overpowered.
Synergies would always be active (even 4 person synergies) so long as 2 or more of the class is 'healthy'. Maybe injured units should count toward synergies. (Incapacitated units do not count for synergies.)
Synergies stack.
Details
Some examples broken down by class
- Mage: 2 mages would have the capacity to SILENCE casters (a chance on an enemies turn to have 1 enemy unit's heal or fire ball attack disabled for that turn). 4 mage party RAIN OF FIRE (chance for an additional fire ball attack to be cast against an enemy).
- Rogue: 2 rogues would make a SINISTER PACT (a chance when a party member is attacked for one of the rogues to counter attack the attacker -- this does not interrupt the original attack). 4 rogues are a GUILD OF THIEVES (a chance to give the rogue party an extra turn like the proposed 'trap' skill, and would stack with a trap unfolding a 'master plan' granting 2 additional turns).
- Warrior: 2 warriors would be able to coordinate their defense in a PHALANX (the phalanx gives a chance for a warrior to take an attack rather than 1 of their allies -- an injured warrior never participates in the phalanx if a healthy warrior is available). 4 warriors would be able to route the enemy into a FORCED RETREAT (a chance for an enemy unit to be forced to run away).
- Priest: 2 priests would enable each other to RESURRECT HEAL (a chance when healing an incapacitated ally to heal them fully to healthy status). 4 priests would receive DIVINE PROTECTION (a chance for an extra heal to be cast at the start of the party's turn).
These are great ideas.
You might also want to add them as optional rules for the Mini Mam RPG system.