what does the reaching tree do?

[XER0]

i know what the description says but i don't understand what it means, how does it work? and what does it do? it's my first time using this card and i have no clue what it does

[Batabii • Suikoden I&II HD]

The reaching tree seems to only work for the path after you get it, not the entire crusade. There's another card like this I haven't obtained in a run yet that sounds like it would also only work once or it would be overpowered