Fateful Common

having momentous consequences; of decisive importance

"that fateful meeting of the U.N. when...it declared war on North Korea"

"the fatal day of the election finally arrived"

ominously prophetic

(of events) having extremely unfortunate or dire consequences; bringing ruin

"the stock market crashed on Black Friday"

"a calamitous defeat"

"the battle was a disastrous end to a disastrous campaign"

"such doctrines, if true, would be absolutely fatal to my theory"

"it is fatal to enter any war without the will to win it"

"a fateful error"

controlled or decreed by fate; predetermined

"a fatal series of events"

Momentous, significant, setting or sealing one’s fate.