The card shows its age in its rules text as it makes use of the outdated term "bury." Cards with the bury mechanic have been errata'd to say instead "put a permanent into its owner's graveyard" or "Sacrifice this permanent." In other words, the true cost of playing the Dreadnought is in having creatures with a total power of 12 or more on your board to sacrifice when it enters the battlefield
That, and you didn't mention WHERE you are summoning the monster from
Card art has become more sophisticated since then
Glory and Brave the Elements are similar tricks that used to see a lot of play, and still do, within certain decks
Quina, Qu Gourmet is another good way to get extra creatures, as it tacks an additional Frog token on to any other token creation that you do on your turn
In this deck, even your smallest units can suddenly become formidable attackers thanks to your leader's ability