The destroying angel is poisonous, but I like it because it has such presence.
Literal
Destroying-angel [topic-は] poisonous-mushroom but, presence [subject-が] exists like [reflective-なあ].
シロオニタケ (Amanita virgineoides, a type of destroying angel) is in katakana as standard for species names. 毒菌 (poisonous mushroom) is a mycological term. 存在感がある (has presence/commanding appearance) is a common expression. The contrast of danger and appreciation creates an endearing nature-enthusiast tone.