100 Simple flavorful battlefield effects

[Nifft]

1) A peculiar interaction of arcane magics causes a slight glow in the air. All arcane powers gain a +2 attack bonus for the duration of the encounter.

Encounter-long attack bonuses are too powerful. Give a damage bonus instead.

3) Mists rise from the ground, granting everyone a +2 concealment bonus to all defenses.

This is only a good idea if your group complains about too little grind.

(10) The sun is low in the horizon, attacks made to a square west of your current square are at a -2. Attacks made to square east of your current square is at a +2.

In spite of what I said about attack bonuses, this is great.

15) The Sound or Sight of two large monsters suddenly mating just beyond the battlefield causes everyone to pause for several moments in awkward silence. Anyone undergoing a (Save Ends) effect gets a free saving throw.

Awesome.

25) Weird space time geometry, certain squares are short cuts through space and time. Attacks through them gain reach +1, this extends the reach of any threatened squares through them to adjacent squares.

Moving through or into these squares costs zero.

Any area affects adjacent to these squares also include these squares.
Any area affects that would normally include these squares also includes all adjacent squares.

These squares do not count against range when the ranged attack is through or into them.

erg... this one needs to be tried out and debugged.

How about:

25) Weird space time geometry. Certain squares are Warp squares. Each Warp square has a mate somewhere on the map. If you are in a Warp square, you can move to the square's mate as though they were adjacent. Additionally, if you are in a Warp square, you can make attacks as though you were in the square's mate. However, if you begin or end your turn in a Warp square, you grant combat advantage to all foes until the beginning of your next turn.

Cheers, -- N

 

[darjr]

How about:

25) Weird space time geometry. Certain squares are Warp squares. Each Warp square has a mate somewhere on the map. If you are in a Warp square, you can move to the square's mate as though they were adjacent. Additionally, if you are in a Warp square, you can make attacks as though you were in the square's mate. However, if you begin or end your turn in a Warp square, you grant combat advantage to all foes until the beginning of your next turn.

Cheers, -- N

It is cool, but I'm sure I've seen that one before, at least in a DDM map.

 

[Rechan]

26) Time is funny here. Any effect that ends "on the end of your next turn" lasts one round longer.

27) The broken mirrors/reflective crystals all around the room prevent combat advantage from flanking, but make disorientation even worse; saving throws to shrug off a Daze condition are at a -2.

 

[Nifft]

It is cool, but I'm sure I've seen that one before, at least in a DDM map.

Ah well, I guess all the cool-yet-obvious ideas have already been done. None the less, here are a couple more warp-oriented ideas:

28) Let's Do The Time Warp Again - A sudden planar incursion warps time. For one round only, all creatures may re-roll a single attack, skill check, or saving throw. (Only one. If you have an ongoing "save ends" condition, you may wish to NOT re-roll your attack.)

29) Planar Instability - A sudden planar instability warps space. This happens between rounds, and does not persist. Use it or lose it. As a free action, any creature on the map may Teleport 3 squares. If the creature is trained in Arcana or Acrobatics, it may instead Teleport 6 squares. Any creature which uses this effect grants combat advantage until the beginning of its next turn.

30) Elemental Incursion - A sudden planar incursion amplifies elemental forces. For one round, all creatures gain Vulnerable 5 to Acid, Cold, Fire, Lightning, and Thunder.

Cheers, -- N

 

[FireLance]

A chaotic whirlwind rampages through the battlefield! All combatants are slid 1d6 squares in a random direction.

Characters trained in Nature realize that the whirlwind is controlled by a mischevous spirit of the air. By spending a move action and making a successful Nature check (DC 16 + 1/2 level of the spirit, which should be fairly close to the level of the enemies the PCs are fighting) the character may invoke the spirit's power and slide a creature 1d6 squares. Characters with the primal power source gain a +2 bonus to the Nature check.

 

[On Puget Sound]

32. Mosquitoes, fire ants or wasps are disturbed by the fight and swarm across the battlefield. All "sustain" effects take longer to maintain - free becomes minor, minor becomes move, move becomes standard, standard becomes full round. Any effects that normally require a full round to sustain cannot be sustained. Swarm druids are unaffected by this event, and anyone who knows the "banish vermin" ritual can make a Hard Arcana check as a standard action to end this effect for the entire battlefield.

 

[roguerouge]

Eclipse: Any attacks from creatures on the ground at aerial creatures cause the attacker to suffer the dazed condition during the following round.

 

[Hussar]

A small animal bursts from a nearby bit of cover and dashes between two combatants. One combatant is startled by the event and the other takes advantage.

Effect: Choose two combatants in melee range. Switch them in initiative order.

 

[Thornir Alekeg]

24) The ground is very muddy, not unlike quick sand, but much firmer. Spending more than one round in one spot means their slowed until the end of their turn. They've sunk up to their ankles in mud.

I know it goes against part of your post, but I like it.

Edit: maybe the characters know but the monsters do not? At least initially?

How about reducing any forced movement by half (minimum 1) instead.

 

[Thornir Alekeg]

The very ground of the battlefield sings with its thirst for blood. When you kill an opponent, your next attack does an additional 3 points of damage.