[Touc]

Destroying Yggdrassil to nullify its healing/killing vines to get them to go away should be a viable strategy, but because of Pond and other heals that sustain combines them with it becomes extremely difficult if not impossible to kill either in reasonable time (not to mention how bad of an idea swapping targets off the summoner is in the first place).

Summons like Ygg shouldn't be able to be healed so that if someone chooses to target them at the expense of dealing damage to their summoner, they aren't just futilely hitting. I'm pretty sure the only thing that can reliably kill Ygg while Pond exists is Styx.