Historical clue formulations

• Get really serious really quickly — 2022-05-11
• Increase quickly — 2019-08-11
• Intensify — 2009-09-05
• Intensify — 2003-07-18
• Heat up — 2000-07-23
• Snowball — 1998-07-02
• Step up — 1997-03-15
• Step up — 1996-05-14
• Mount — 1995-09-09
• Step up — 1995-06-11
• Mount — 1995-06-10
• Raise — 1994-12-03