Yes friends, another topic for ideas for spells in a guild. Are you surprised? Elementalists are perhaps the worst rounded in terms of spell diversity. They don't have a whole lot of innovative or exciting spells so there's likely to be plenty of room to improve and brainstorm here. Here's an idea from the 'idea' command:
A spell that puts a gateway to an elemental plane into a room. If somebody is in a room, there is an X % chance of a random elemental, ranging from lesser to dragon, to enter the room and be mean. If somebody is crazy enough to enter, they enter a warp-like environment that does serious elemental damage of whatever lore to the caster (unless transformed or highly protected), as well as having elementals come and attack the entrant until they leave. The gateway can be dispelled by dispel magic. (possibly by dispel rune but not necessarily, since the gateway should just be a big annoyance, not a serious threat).