Mordekaiser vs Nasus Top Matchup
Mordekaiser Top wins 51.0% of 4,744 Low Elo games against Nasus Top, +0.1 points vs expected, 2-patch window 26.19-26.20.
Researched on LoL patch 26.20. Tips are written to hold at any rank; stats come from Low Elo ranked games up to patch 26.20.
Why Mordekaiser is favored
Mordekaiser's early Q/E pressure can push Nasus off safe stacks, and he can use a freeze when Nasus spends Spirit Fire(E) on the wave. If they duel after level 6, Mordekaiser should cast Realm of Death(R) after Nasus activates Fury of the Sands(R), so his stat steal includes part of Nasus's temporary bonuses.
Measured in High Elo: Mordekaiser wins 1.9pp more often than expected over 1,091 games.
How to play as Mordekaiser
Keep Nasus poked and zone him from farm; use an isolated Obliterate(Q) when he approaches. If Spirit Fire(E) pushes the wave toward you, hold it near your side and deny safe stacks.
Wait for Nasus to activate Fury of the Sands(R) before casting Realm of Death(R), so your stat steal includes part of the temporary bonus.
Fury of the Sands(R) grants Nasus bonus combat stats, and Realm of Death(R) steals a share of the target's core stats; casting after Nasus activates R lets Mordekaiser steal some of those bonuses.
How to play as Nasus
Farm safely and avoid Mordekaiser's Q/E skillshots; do not use Fury of the Sands(R) first. If Realm of Death(R) starts, activate your R afterward so he cannot steal its temporary stats.
Sources
These notes come from r/MordekaiserMains and r/nasusmains, checked against the champions' abilities.