Other creatures that grant this effect are: Souls Attendant (opponents creatures too) Soul Warden (opponents creatures too) Suture Priest In addition to the two list above, Authority of the Consuls will give you 1 life every time a creature enters the battlefield under an opponents control
As a quick related aside, theres a common anti-Reserved List argument that most of these cards will hold their value even though a reprint because even if they print more Underground Seas, they arent going to print any more Beta Underground Seas
Counterspell (Ice Age/Alliances, Tempest/Stronghold/Exodus, Masques/Nemesis/Prophecy) Counterspells are decent in limited, but by no means the be-all, end-all of the universe
Copying auras is another way to get great value
Don't have something to Shock and your foe's life is too high to shoot
Do you feed the fish? is a question as old as Commander, and because of this infamy, many times the Mystic Remora player will sit back and watch as nothing happens for several turns until, eventually, the cumulative upkeep cost becomes too exhaustive, the Mystic Remora is sacrificed, and suddenly the game begins in earnest