I get the general idea but your wording is very bad I had to read it three times to understand it, also what about the minion’s body? Anyway your fix seems completely counter-intuitive and doesn’t solve the general issue about rush.
I suggest to rework the rush mechanic the following way:
" can move OR attack immediately"
See? I changed ONE WORD . It will be now much easier to play around tiger since you can just run away and be safe. If you want to use tiger efficiently you will actually need a certain board state, or play several minions to create a chain to reach the opponent. I think this nerf is fair, it doesn’t kill rush while giving you the opportunity to play around it and interact with it.
Let see what impact it would have on the current rush minion roster:
-Saberspine Tiger: would be fine, as a basic neutral card, it should not be that strong anyway
-Makantor warbeast: would be still good in the majority of the situations.
-Spectral revenant: probably the least affected minion but still a welcome little nerf.
-Elucidator: would probably need a little buff but a well deserved rework IMO , this card is currently stupid.
-Rasha’s curse/star’s fury: They would both be fine.
-Obelisk: Would need a rework
-Tusk boar: Would need a rework