Collapse Portal

This rare magic can seal the crystal sphere in which a fantasy world floats. The spell is unreliable; the caster must make an Intelligence check to avoid failure. If a create portal spell was cast during the past turn within a 1-mile radius, the check is made at a 3-point penalty.

If the check succeeds, the crystal sphere seals. If the two-round casting time brings a ship to the sphere's shell as spellcasting is completed, roll a 1d10 to determine just when the sphere closes (see table).

1d10 | Result ------+----------------------------------------------------------------------------------- 1 - 2 | Portal closes before the ship reaches the sphere; ship must turn or ram the shell. 3 - 5 | Portal closes as the ship reaches the sphere; ship unavoidably rams the shell. 6 - 9 | Portal closes on the ship, cutting it cleanly into two pieces. 0 | Portal closes just after ship passes through.

A ship ramming or being cut by a crystal sphere sustains both collision damage and spelljammer shock (the helmsman must save vs. spell or die).

A ramming ship suffers loses 10 hull points (a ship with 0 hull points breaks up). The ship rings with the impact, and all those not sitting or firmly tied down have a chance to lose their balance and fall. Those with Dexterity scores must make a Dexterity check of fall prone, while those without have a flat 40% chance to fall.

A bisected ship also breaks up immediately, its atmosphere dividing between the two parts of the ship. Decide randomly where the break occurs. All beings at risk should save vs. death magic at +3 to avoid being slain by the closing shell, and any items at risk must save vs. disintegration to avoid destruction.

Few know how to cast this spell, though almost every space faring being has heard dark tales of it cutting ships in half as a crystal sphere closes.

The material components are two smooth stones of any size, one of diamond and the other of obsidian.

Notes: Rare in spelljamming cultures; otherwise unknown.