[RPG] How to summons and beast companions become more fun

Combat is frustrating when you are unable to act. Combat is challenging when you are threatened, at risk, but able to respond.

In order to reduce frustration, make things that reduce actions with save-ends effects staged. A stun or dominate should never be the first thing dropped on someone with a save-ends (End of next turn is fine, however.)

I prefer using the progression of: Granting Combat advantage, dazed, stunned for my save-ends effects that were originally stunned, and dazed -> Dominated for my dominates, especially if they originate from an at-will.

The best way to make combat challenging and exciting is to scatter terrain features that both allies and enemies can use to great (and lethal) advantage while stationing fairly beefy enemies at them. Then the combat has a sub-goals of, for example "control the [really nasty thing shooting fire at us] and reorient it so we can rain fire on the enemies" as opposed to the "clear the battlefield." By increasing tactical complexity, you increase the challenge, but also increase the opportunities for innovative tactics and player self-expression.

In a campaign I recently ran, a rogue/assassin run by one of my players betrayed the party. He only partially disguised the fact that he was an assassin, so the party was always a little wary of him. However, he had always participated in combats and done little (that they ever spotted or knew about) to betray their trust. Secretly, he stole a couple of critical artifacts from party members while they slept in camp and it was his watch. His betrayal also waited for the party to enter into a major combat (3.5e rules btw).

During the first couple of rounds of combat the party's main fighter was slain (taken to something like -25 HP). When the fighter went down, the assassin passed me a note that he was holding his action for the cleric's attempt to raise him. The party's cleric was about to cast Revenance to restore him to life when the assassin let loose his sneak attack. The cleric's spell was wasted, the fighter remained dead and the cleric had no other spell prepared to help that day. The bard was about to use the artifact (a Zagyg's token which would have provided a limited wish) to revive the fallen fighter or restore the cleric's spell, only to discover that he could not find it any longer (having been stolen by the assassin in the previous night's camp). The rest of the party fled, pausing only long enough to kill the betrayer.

A couple other ideas he had were to secretly replace the party's magical weapons with non-magical replicas. I ruled the in-game story & timeline wouldn't allow him enough time to carry out that plan, but it might be an idea for you. He also got the party's fighter to accept an intelligent, magical weapon as his main weapon. The weapon did not reveal itself and later (long after the assassin's death) took control of the fighter to carry out its own agenda, thus slipping the betrayal even further into the party and story.