I know these cards have been talked about before, and I too jumped on the band wagon of them being poorly worded.
Here's how I played it in my first couple of games:
Beastmaster simply gets dealt 2 shadow cards instead of 1
Chieftan attacks first time with 3, then next with 5, etc.
However, over the weekend, I realised that I'd probably been playing the Chieftan wrong. I now think he gets the resource token as soon as he attacks, since it is the same wording. So he is declared as an attacker, he gets the resource token straight away.
Both these cards need clarifying and possibly rewording. When exactly is "After the attack"? As it is declared as an attacker or after the attack is resolved. If the latter, then adding an extra shadow card to the Beastmaster after the attack has resolved is a bit pointless