Frieza - new troops suggestion

Like healer flies above healing ground troops, Frieza could freeze enemy's defensive buildings at a range of 3-5 tiles, for game balancing. Frieza has HP lower than Healer, dies instantly if struck by air bomb. Upgrades will increase freezing rate of Frieza or the time it would keep the defence frozen or maybe even it's range. To make it more interesting, the type of upgrade will decide which stat to boost. Elixir upgrade will increase rate of freezing. Dark elixir upgrade increases time to keep defence frozen, while a combo of elixir and dark elixir increases range. At every upgrade, the amount if stat that could increase will vary. That amount of every stat will be maximum at first upgrade. By the second upgrade, the amount will be halve and so on... So, the user must decide what stat to upgrade. Once upgraded, it can't be cancelled or reverted. The laboratory will show 3 choices of Frieza - each will have same level but different upgrade costs as mentioned above. Suggestions please...