Melanie Smith will be sentenced on 8 May for murdering five members of the same family in a flat fire in Prestatyn.
Mr Justice Griffith-Williams warned the 43-year-old that she should expect a life sentence.
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Yellow and amber warnings of strong winds remain in place across Wales, as Storm Doris batters the UK.
Trees are being brought down by strong winds from storm Doris.
The 2017 Champions League final will be the biggest event ever held in Wales.