The phrase "match in the powder barrel" is a metaphor that refers to a situation or action that could potentially cause a disastrous outcome. To express this idea in various ways, there are many synonyms that can be used. Some of these include "ticking time bomb," "lighting a fuse," "playing with fire," "walking on thin ice," "pushing one's luck," "tempting fate," "inviting disaster," "risking catastrophe," and "courting trouble." Each of these words and phrases underscores the danger or recklessness inherent in the original metaphor, and can be effective in conveying the seriousness of a situation where even the slightest misstep could lead to catastrophic results.