greninja full art pokemon card V - 073/264 Promo Card Type Taking a closer look at

A solid recommendation is to toss at least one counter on Siege Veteran itself to help it dodge at least some removal, like Cut Down

At the beginning of your end step, if there are cards exiled with this enchantment, put them into their owner's graveyard, then this enchantment deals that much damage to each opponent

It can be OK in combo decks without black or blue (for some mad reason) that want to protect against things like Duress, all be it badly

Prophet of Kruphix has a similar untap ability, but when combined with the Prophets You may cast creature spells as though they had flash ability, the card was too good and was banned from Commander

The one toughness at first glance does make the card look dodgy however when you realise you can both pump the card and make it indestructible with zero mana sacrifices the low toughness is pretty irrelevant