Can you float all your mana in response to Ekko's deathnell trigger before it resolves, effectively doubling your available mana?

Ruling: Yes, you can float Energy in response to Ekko's deathnell trigger. The floated Energy will remain available until end of turn, allowing you to have both the floated Energy and the Energy from the deathnell effect.

Sequence:

• Ekko dies and deathnell triggers
• In response to the trigger, tap all your mana to float it
• When deathnell resolves, you gain additional mana
• You now have access to both the floated mana and the newly gained mana

Nuances:

• Floated Energy does not disappear until the end of the turn