This enemy has an extremely long range and decent damage, but its low movement speed makes it easy to stall.
Strategy
Like Codename "Red Riding", you must keep Ramiel far away from your base at all costs, lest he one-tap your base due to his Base Destroyer. Thankfully, the stages he appears in are very long, giving you a bit of breathing room. Tanky and fast units like Crazed Cow Cat or Jamiera Cat are able to stall Ramiel well under the correct conditions. Using units like Polevaulter Cat and other units with a long range that can reach the base from far away is a good idea due to Ramiel's range.