Whenever you scry, put a +1/+1 counter on each of up to X target creatures, where X is the number of cards looked at while scrying this way.
Whenever a creature you control with a +1/+1 counter on it becomes the target of a spell or ability an opponent controls, you may draw a card.
Elrond turns every scry into a counter-distribution engine, fattening your whole board while the second ability punishes opponents for trying to interact with your beefed-up creatures. You ramp into scry payoffs early, snowball wide and tall counter synergies in the mid-game, and close with an overwhelming counter-heavy battlefield or a few oversized threats backed by card advantage.
Turns cheap, repeatable scry effects into board-wide stat growth
Built-in card draw discourages opponents from removing your creatures
Scales counters as wide as your board (up to X creatures)
Blue-green gives access to premium ramp, draw, and counter synergies
Board wipes erase your counter investment in one card
Relies on scry enablers actually being on the battlefield to function
Counters alone don't grant evasion or protection without support
Can be slow to come online if you lack early scry sources