Basically Dack is below the power level of good walkers when unable to use the -2 ability and quite significantly better pretty much whenever he can, certainly on average
Also you have to take into account Japanese quality control, under this scenario MF has knowledge of the errors and allows product to leave warehouses etc
If this card battles against a Defense Position monster, destroy that card at the end of the Battle Phase
There will need to be a personal or communal selection of land cards, so that players can build a 40 card deck from the 42 card selection, including extra Land cards to ensure they can power their spells
Some examples: Five is a lot, especially when you only pay three mana to get them
When a Rock-Type monster is sent to the Graveyard (except during the damage step): You can Special Summon this card from your hand