Oh your team is winning, but the enemy team somehow stole the Elder Dragon. I guess your team loses now.
Which human being thought that a buff than instant executes at a certain threshold is a good idea? Remember when people wanted damage to be lower, oh never mind when your 4000 HP tank has an effective 3200 HP.
Either remove the Elder Dragon buff.
Give it a proper cooldown, so if one target gets executed, the rest of the team is immune to the execute effect.
Make the Elder Dragon buff a special skillshot ability.