This depends so much on what the board position is like. In most cases, there aren't more than 3 legal attacks, so an additional one is entirely worthless. When it can be set up one extra attack would often net you one extra kill, making up the Magic point, so I would always pay 1 Magic for an attack. From a game theory perspective, that indicates that the price is far too low, and that adding attacks is worth more that 1 Magic each. However, Tundle's ability is fairly costed. Since there are turns where extra attacks are completely wasted, gaining even a small amount of Magic, like 1 Magic per two attacks, is a complete no-brainer.
Originally Posted by Richard III
As in the quote above, there is no fixed exchange rate. Having four attacks one turn and two the turn after that isn't even close to an even trade in any situation that you would agree to make the trade in.
How much I'd pay to move an extra Unit is dependent entirely on how easily my opponent can buy an extra attack to kill the Unit I moved.
Carl the Sword Grounder has seen worse than . . .