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You enter the cavernous Inner Fane, a symmetrical chamber built of dark stone with a sickly green hue. Its ceiling stretches up into darkness, upheld by a circle of pillars that converge into pointed arches. The air hangs thick with the occult.

Concentric steps lead down to a central altar at the chamber's nadir, an island surrounded by a shallow blood pool. Black ceremonial candles stand on bronze sconces; their flames cast the long shadows of the pillars across the fane. Arched alcoves recessed along the Fane's perimeter hold reservoirs of blood, which slowly flows down through channels in the smooth, stone floor.

In my D&D Quick Tip on building memorable boss battles, I mentioned that creating an epic battleground was an integral part of the process. Since my Disciples of Dreth'dor campaign has finally reached its Act I boss battle, I figured I would share the battlefield I created and explain the design philosophy behind it.

The battleground is known as the Inner Fane, the temple of a vampire drow priestess around which was created a larger temple -- the Outer Fane. This will be the first post in a mini-series on the design aspects of this boss fight.

Size

It's difficult to create an epic battlefield that doesn't feel epic in size. The Inner Fane measures approximately 240 feet in width -- that's just under 50 squares. While at most 50% of the area will actually be used in combat (more on that later), the key is that the battlefield feels large.

If you don't have the space or resources to lay out a huge battlemap, you can get away with the illusion of scale by employing an epic backdrop. A battle that takes places on a normal-sized platform three thousand feet in the air will feel epic -- what's a bigger backdrop than the sky?

Special Effects

Michael Bay and George Lucas get a lot of flack for their overuse of special effects, but that's because their work is "all flash, no substance." When it comes to your epic boss fight, you don't want to get stingy on the special effects -- especially since the power of imagination grants you an unlimited budget.

While not, technically, a special effect, the unsettling amount of blood I included was largely intended for visual effect. The crimson is immediately striking to the eye, contrasting sharply with the green stone, and when the realization that it's blood hits, it imparts a certain psychological effect.

Twenty-four faintly glowing runes that pulse with energy run along the perimeter of the central pool, and, though they're not depicted, wisps of green energy swirl around the central island.

Another special effect comes in the form of a blood ritual being conducted as the PCs enter. The vampire priestess stands at the Fane's center, while 23 bloody acolytes stand between the pillars. Their blood drops float through the air, in defiance of gravity, slowly coalescing with a globe-sized blood orb that hovers before the vampire.

Lastly, walls of green fire periodically flare up from the thick blood ring, triggered magically by the vampire.

Movement

Any good battlefield needs to allow and encourage movement. What's the point of a huge chamber if the PCs won't stray more than a couple squares from where they began the battle?

The actual combatants factor into this aspect of planning. The PCs would be outnumbered: four heroes versus one Elite Artillery and her 23 Soldier Minions.

The southern passage -- from where the PCs would enter -- is a great choke point for the players to hold. However, to uncork the bottle after a couple rounds, the vampire -- a Drow Arachnomancer -- casts an area burst spell that lasts throughout the encounter, damaging anyone who stays in the passage.

The blood ring acts as Difficult Terrain, or Challenging Terrain if the player chooses not to treat it as difficult terrain, requiring a Balance check to avoid slipping and falling prone. The ring psychologically divides the battlefield in half, and the players can choose to tactically fight near it to reduce the enemies' ability to shift.

The blood pool uses the same rules as the blood ring and makes simply charging the vampire a less inviting option, especially when coupled with...

The Sacred Circle, those wisps of green energy that swirl around the central island. It grants the vampire a +2 bonus to attack rolls for as long as she stands within it. The PCs can sludge through the blood pool and fight an uphill battle within the Sacred Circle, but drawing the vampire out of this clearly advantageous position presents itself as the more viable strategy.

The blood reservoirs in the alcoves are five feet deep -- large enough for a desperate character to submerge himself and effectively disappear for as long as he can hold his breath. One PC was granted an extremely powerful ability by a deity -- for this battle only -- that recharges roughly every six rounds.

The central pillars serve as cover from the vampire's ranged attacks, as well as obstacles to reduce the number of enemies that can surround the PCs.

The runes around the blood pool are Runes of Power; anyone who spends a Standard Action to touch one absorbs its power, regains the use of a spent Encounter Power, and depletes its magic. Having 24 of these may seem incredibly overpowered; however, the PCs had fought through a few battles without an extended rest, and were out of healing surges and Daily Powers.

The green fire the springs up from the blood ring forms a semicircle in the southern half of the Fane, grants concealment, and damages anyone who passes through it. This is a failsafe in case players remain near the southern passage and use ranged attacks, encouraging them to circle around to the northern half of the chamber.

Combined, these elements give the PCs options, create a point of contention at the chamber's center, and encourage circular movement around the battlefield.